# 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.

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.

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?

Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
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
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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 ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
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
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
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.
what is nano technology
what is system testing?
Jeannette has $5 and$10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
What is the expressiin for seven less than four times the number of nickels
How do i figure this problem out.
how do you translate this in Algebraic Expressions
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)=
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?