Exercise 1 Page 124

Let's start by recalling that the percent proportion is a proportion that sets the ratio of a part of a whole equal to the ratio of a percent out of 100. part/whole=percent/100 We want to find what percent of $ 90 is $ 9. Let n represent the percent. $ 9/$ 90=n/100 Now we can solve the proportion we got for n. Let's do this by using the fact that the cross products of any proportion are equal. To make the math easier, we will ignore the dollar unit.

9/90=n/100

CrossMult

Cross multiply

9* 100= 90 * n

Multiply

Multiply

900=90n

Finally, we will use the Division Property of Equality to get the value of n.

900=90n

DivEqn

.LHS /90.=.RHS /90.

900/90=90n/90

CancelCommonFac

Cancel out common factors

900/90=90n/90

SimpQuot

Simplify quotient

900/90 = n

CalcQuot

Calculate quotient

10 = n

RearrangeEqn

Rearrange equation

n = 10

We got that n= 10 is a solution to the proportion. This means that $ 9 is 10 % of $ 90.