Exercise 20 Page 274

Let x represent the unknown number. Write and solve a percent equation using x.

Equation: 85 % * x=10.2
Solution: x=12

Practice makes perfect

We know that 85 % of a number is 10.2 Let x be this unknown number.

We can write this relationship as a percent equation using x. 85 % * x=10.2 We will solve this equation using the Multiplication and Division Property of Equality. Let's do it!

85 % * x=10.2

a %=a/100

85/100 * x=10.2

a/c* b = a* b/c

85x/100= 10.2

LHS * 100=RHS* 100

85x/100* 100 =10.2 * 100

a/100* 100 = a

85x = 10.2* 100

85x = 1020

Next, we will use the Division Property of Equality to simplify the equation even further.

85x=1020

.LHS /85.=.RHS /85.

85x/85=1020/85

Simplify quotient

x=1020/85

Calculate quotient

x=12

We have that 10.2 is 85 % of 12.

1 Fractions, Decimals and Percents p.273

2 The Percent Proportion p.273

3 The Percent Equation p.274

4 Percents of Increase and Decrease p.274

5 Discounts and Markups p.275

6 Simple Interest p.275

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