Percents And Probability Worksheet With Answers - Lesson 12-19 Page 30
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49sOlving Percents using eQuatiOns
Lesson 17
B
eatrice and Carmen were shopping at the mall. Beatrice found a shirt she liked that was originally $46.
It was on sale for 20% off . She needed to fi nd what 20% of 46 was to fi gure out the discount. She did the
problem using proportions. Carmen did it another way using a decimal for the percent. Th eir methods
are shown below.
Beatrice
Carmen
using a Proportion
using a decimal and an equation
Set up a proportion using a ratio for the percent.
Write 20% as a decimal.
0.2
percent
part
= x __
20
___
Multiply 0.2 by 46 to fi nd the part needed.
100
46
whole
x = 0.2 ∙ 46
Solve the proportion.
100x = 920
x = 9.2
x = 9.2
She will save $9.20.
She will save $9.20.
Both methods work. Beatrice and Carmen both found Beatrice would save $9.20. Why did Carmen’s
equation work? Take a look.
= x __
20
___
Write a percent proportion.
100
46
0.2 = x
___
Write the percent as a decimal.
46
0.2 ∙ 46 = x
___
Multiply both sides by 46.
∙ 46
46
Simplify.
0.2 ∙ 46 = x
9.2 = x
Th is shows that the percent equation is a direct result of solving a proportion and is just another way to
solve percent problems.
100
Lesson 17 ~ Solving Percents Using Equations
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