# 9.7 Solve a formula for a specific variable  (Page 5/9)

 Page 5 / 9

Solve the formula $-5x+y=-1$ for $y.$

Solve the formula $4x+3y=7$ for $y.$

$y=\frac{7-4x}{3}$

Solve the formula $3x+2y=11$ for $y.$

Solve the formula $x-y=-4$ for $y.$

y = 4 + x

Solve the formula $x-y=-3$ for $y.$

Solve the formula $P=2L+2W$ for $L.$

$L=\frac{P-2W}{2}$

Solve the formula $P=2L+2W$ for $W.$

Solve the formula $C=\pi d$ for $d.$

$d=\frac{C}{\pi }$

Solve the formula $C=\pi d$ for $\pi .$

Solve the formula $V=LWH$ for $L.$

$L=\frac{V}{WH}$

Solve the formula $V=LWH$ for $H.$

## Everyday math

Converting temperature While on a tour in Greece, Tatyana saw that the temperature was $\text{40°}$ Celsius. Solve for $F$ in the formula $C=\frac{5}{9}\left(F-32\right)$ to find the temperature in Fahrenheit.

104° F

Converting temperature Yon was visiting the United States and he saw that the temperature in Seattle was $\text{50°}$ Fahrenheit. Solve for $C$ in the formula $F=\frac{9}{5}C+32$ to find the temperature in Celsius.

## Writing exercises

Solve the equation $2x+3y=6$ for $y\text{:}$

1. when $x=-3$
2. in general
3. Which solution is easier for you? Explain why.

Answers will vary

Solve the equation $5x-2y=10$ for $x\text{:}$

1. when $y=10$
2. in general
3. Which solution is easier for you? Explain why.

## Self check

After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.

Overall, after looking at the checklist, do you think you are well-prepared for the next Chapter? Why or why not?

## Use a Problem Solving Strategy

Approach Word Problems with a Positive Attitude

In the following exercises, solve.

How has your attitude towards solving word problems changed as a result of working through this chapter? Explain.

Answers will vary.

Did the Problem Solving Strategy help you solve word problems in this chapter? Explain.

Use a Problem Solving Strategy for Word Problems

In the following exercises, solve using the problem-solving strategy for word problems. Remember to write a complete sentence to answer each question.

Three-fourths of the people at a concert are children. If there are $87$ children, what is the total number of people at the concert?

There are 116 people at the concert.

There are $9$ saxophone players in the band. The number of saxophone players is one less than twice the number of tuba players. Find the number of tuba players.

Reza was very sick and lost $\text{15%}$ of his original weight. He lost $27$ pounds. What was his original weight?

His original weight was 180 pounds.

Dolores bought a crib on sale for $\text{350}.$ The sale price was $\text{40%}$ of the original price. What was the original price of the crib?

Solve Number Problems

In the following exercises, solve each number word problem.

The sum of a number and three is forty-one. Find the number.

38

Twice the difference of a number and ten is fifty-four. Find the number.

One number is nine less than another. Their sum is twenty-seven. Find the numbers.

18, 9

The sum of two consecutive integers is $-135.$ Find the numbers.

## Solve Money Applications

Solve Coin Word Problems

In the following exercises, solve each coin word problem.

Francie has $\text{4.35}$ in dimes and quarters. The number of dimes is $5$ more than the number of quarters. How many of each coin does she have?

16 dimes, 11 quarters

Scott has $\text{0.39}$ in pennies and nickels. The number of pennies is $8$ times the number of nickels. How many of each coin does he have?

#### Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Good
Berger describes sociologists as concerned with
Mueller Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply

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