Math Connects, Course 3 131

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The percent equation is an equivalent form of the percent

proportion in which the is written as a

.

BUILD YOUR VOCABULARY (pages 116–117)

EXAMPLE Find the Part

Find 30% of 450.

Estimate 10% of 450 is 45. So, 30% of 450 is 3 · 45 or 135.

The percent is . The whole is . You need to fi nd the

part. Let n represent the part.

part = percent · whole

n = · Write the percent equation.

n = Multiply.

So, 30% of 450 is .

EXAMPLE Find the Percent

102 is what percent of 150?

Estimate 102 _ 150

≈ 100 _ 150

or 66 2 _ 3 %

The part is . The whole is . You need to fi nd the

percent. Let n represent the percent.

part = percent · whole

= n · Write the percent equation.

102 _ 150

= 150n _ 150

Divide each side by 150.

= n Simplify.

Since = %, 102 is % of 150.

Algebra: The Percent Equation5–7

MAIN IDEA

• Solve problems using the percent equation.

Explain how to write a decimal as a percent. (Lesson 5-2)

REVIEW IT

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5–7

132 Math Connects, Course 3

Copyright ©

Glencoe/M

cGraw

-Hill, a division of T

he McG

raw-H

ill Com

panies, Inc.EXAMPLE Find the Base

144 is 45% of what number?

Estimate 144 is 50% of 288.

The part is . The percent is . You need to fi nd the

whole. Let n represent the whole.

part = percent · whole

= · n Write the percent equation.

144 _ 0.45

= 0.45n _ 0.45

Divide each side by 0.45.

= n Simplify.

So, 144 is 45% of .

Check Your Progress Find the part, percent, or base.

a. Find 20% of 315. b. 135 is what percent of 250?

c. 186 is 30% of what number?

EXAMPLE Solve a Real-Life Problem

SALES TAX The price of a sweater is $75. The sales tax is

5 3 _ 4 %. What is the total price of the sweater?

You need to fi nd what amount is 5 3 _ 4 % of $75.

Let t = the amount of tax.

t = · Write the equation.

t = Simplify.

The amount of tax is . The total cost of the sweater

is $75 + or .

Check Your Progress The price of a pair of shoes is $60. The sales tax is 5 percent. What is the total price of the shoes?

ORGANIZE ITWrite the percent equation in words and symbols. Explain why the rate in a percent equation is usually written as a decimal.

Lesson 5-7

®

HOMEWORKASSIGNMENTPage(s):

Exercises:

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