1. Percents A percent is a ratio that compares a number to 100.
Rewrite a percent as a fraction or a decimal and multiply:
60% = 60/100
60% = .60
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2. Percents (using the percent proportion)
Types of percent problems:
Type
Example
Proportion
Find the Percent
What percent of 5 is 4?
Find the Part
What number is 80% of 5?
Find the Whole
4 is 80% of what number?

3. Percents (using the percent equation). part = % · whole
Percents (using the percent equation) part = % · whole *remember to turn the percent into a decimal
Types of percent problems:
Type
Example
Equation
Find the Percent
3 is what percent of 6?
3 = n(6)
Find the Part
What number is 50% of 6?
p = 0.5(6)
Find the Whole
3 is 50% of what number?
3 = 0.5(w)

4. Percent of Change (pg. 346)
A percent of change is a ratio that compares the change in quantity to the original amount.
Equation: percent of change = amount of change
original amount
= final amount – original amount

5. Percent of Change (pg. 346)
Percent of Increase – the percent of change is positive
Percent of Decrease- the percent of change is negative

6. Sales Tax and Tips (pg. 351) Sales tax:
Additional amount of money charged on items people buy;
Total cost = regular price + sales tax
Method 1 :
Add sales tax to the regular price.
Example: $ % sales tax
Calculate 5.75% of Use the percent equation; t = x t = 8.05
Add $8.05 to the price for a total of $148.05

7. Sales Tax and Tips (pg. 351) Sales tax:
Additional amount of money charged on items people buy;
Total cost = regular price + sales tax
Method 2 :
Add percent of tax to 100%
Example: $ % sales tax
100% % = %
Multiply 140 x = ; Total cost including tax = $148.05

8. Sales Tax and Tips Tip or gratuity:
A small amount of money in return for a service. The total price is the regular price of the service plus the tip.
Method 1 :
Add tip to regular price
Example: 15% of $35
0.15 x 35 = 5.25
Add the tip to the regular price for total cost; $ $35.00 = $40.25

9. Sales Tax and Tips Tip or gratuity:
A small amount of money in return for a service. The total price is the regular price of the service plus the tip.
Method 2 :
Add percent of tip to 100%
Example: 15% of $35
100% + 15% = 115%
Express 115% as a decimal = 1.15
Multiply 1.15 x 35 = 40.25
Total cost = $40.25

10. Sales Tax and Tips Tip or gratuity:
A small amount of money in return for a service. The total price is the regular price of the service plus the tip.
Method 2 :
Add percent of tip to 100%
Example: 15% of $35
100% + 15% = 115%
Express 115% as a decimal = 1.15
Multiply 1.15 x 35 = 40.25
Total cost = $40.25