Exercise 2 Page 251

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. We can represent a is p percent of wwith the given proportion. part/whole=percent/100 ⇔ a/w=p/100We can find what percent 42 of 80 is by thinking about 42 as the part of a whole and 80 as the whole. Let's substitute a= 42 and w= 80 into the formula and solve for p using the Properties of Equality.

a/w=p/100

SubstituteII

a= 42, w= 80

42/80=p/100

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Solve for p

MultEqn

LHS * 100=RHS* 100

42/80* 100=p/100 * 100

FracMultDenomToNumber

a/100* 100 = a

42/80* 100=p

MoveRightFacToNum

a/c* b = a* b/c

42* 100/80=p

Multiply

Multiply

4200/80=p

CalcQuot

Calculate quotient

52.5=p

RearrangeEqn

Rearrange equation

p= 52.5

Knowing the value of p, let's look at the completed percent proportion. 42/80=52.5/100 We found that 42 is 52.5 % of 80.