Exercise 4 Page 249

The percent equation is an equation in which the part is equal to the product of the corresponding percent and the whole. We can represent a is p percent of wwith the following equation. a= p% * wWe can find what percent of 20 is equal to 18 by substituting a= 18 and w= 20 into the formula and solve for p% using the Properties of Equality.

a= p% * w

SubstituteII

a= 18, w= 20

18= p% * 20

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Solve for p%

DivEqn

.LHS /20.=.RHS /20.

18/20=p% * 20/20

CancelCommonFac

Cancel out common factors

18/20=p% * 20/20

SimpQuot

Simplify quotient

18/20=p%

CalcQuot

Calculate quotient

0.9=p%

RearrangeEqn

Rearrange equation

p%= 0.9

Since 0.9 equals 90%, we can complete percent equation. 18= 90% * 20 We found that 18 is 90 % of 20.

Checking Our Answer

Checking Our Answer

We can use a model to check our answer.