(7) Lesson 2.7

1. Course 2, Lesson 2-7
Find the total cost to the nearest cent.
1. $100 dinner; 20% gratuity
2. $12,300 car; 5% sales tax
3. $12 book; 8.5% sales tax
4. Jordan’s total phone bill was $85. It included the usage charges plus
a 3% state surcharge. What was his actual charge for phone usage?
5. The total cost for a plumber was $190. This included the installation
fee plus a 7% service fee. What was the installation fee?
6. Alexa and Jorge ordered Chinese food delivered to their home. The
total bill was $36. This included $34.29 for the food and a delivery
charge. What percent of the bill was the delivery charge?

2. Course 2, Lesson 2-7
ANSWERS
1. $120
2. $12,915
3. $13.02
4. $82 . 52
5. $177 . 57
6. 5%

3. HOW can percent help you understand
situations involving money?
Ratios and Proportional Relationships
Course 2, Lesson 2-7

4. Ratios and Proportional Relationships
Course 2, Lesson 2-7 Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council
of Chief State School Officers. All rights reserved.
• 7.RP.3
Use proportional relationships to solve multistep ratio and percent
problems.
• 7.EE.3
Solve multistep real-life and mathematical problems posed with
positive and negative rational numbers in any form (whole
numbers, fractions, and decimals), using tools strategically. Apply
properties of operations to calculate with numbers in any form;
convert between forms as appropriate; and assess the
reasonableness of answers using mental computation and
estimation strategies.

5. Ratios and Proportional Relationships
Course 2, Lesson 2-7 Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council
of Chief State School Officers. All rights reserved.
Mathematical Practices
1 Make sense of problems and persevere in solving them.
3 Construct viable arguments and critique the reasoning of others.
4 Model with mathematics.
5 Use appropriate tools strategically.

6. • To calculate the sale price of an
item after a discount or markdown
• How to determine the better buy
Ratios and Proportional Relationships
Course 2, Lesson 2-7

7. Ratios and Proportional Relationships
Course 2, Lesson 2-7
• discount
• markdown

8. 1
Need Another Example?
2
3
4
5
6
Step-by-Step Example
1. A DVD normally costs $22. This week it
is on sale for 25% off the original price.
What is the sale price of the DVD?
Subtract the discount from the regular price.
First, find the amount of the discount. Let d represent the discount.
Write the percent equation.
25% = 0.25.d = 0.25 22
Multiply.d = 5.50
Next, subtract the discount from the regular price. $22 – $5.50 = $16.50
Subtract the percent of discount from 100%.
100% – 25% = 75% Subtract the discount from 100%.
The sale price is 75% of the regular price. Let s represent the sale price.
Write the percent equation.
75% = 0.75.s = 0.75 22
Multiply.s = 16.50
The sale price of the DVD is $16.50.7
part = percent whole
part = percent whole

9. Answer
Need Another Example?
A box of golf balls sells for $20. This week it
is on sale for 30% off of the original price.
What is the sale price of the set?
$14

10. 1
Need Another Example?
2
3
Step-by-Step Example
2. A boogie board that has a regular price of $69 is on sale at
a 35% discount. What is the sale price with 7% tax?
Find the amount of the discount.
Let d represent the discount.
Write the percent equation.
35% = 0.35.d = 0.35 69
Multiply.d = 24.15
Subtract the discount from the regular price.
$69 – $24.15 = $44.85
The percent of tax is applied after the discount is taken.
7% of $44.85 = 0.07 44.85
= 3.14
$44.85 + $3.14 = $47.99
The sale price of the boogie board including tax is $47.99.
Write 7% as a decimal.
The tax is $3.14.
Add the tax to the sale price.
part = percent whole

11. Answer
Need Another Example?
Sandra is buying decorations for a party. She
wants to buy a set of balloons. The original cost
of the balloons is $39, but the store is offering a
25% discount. What is the sale price of the
balloons including 5.75% tax?
$30.93

12. 1
Need Another Example?
2
3
4
5
6
Step-by-Step Example
3. A cell phone is on sale for 30% off. If the sale
price is $239.89, what is the original price?
The sale price is 100% – 30% or 70% of the original price.
Let p represent the original price.
239.89 = 0.7 p
Divide each side by 0.7.
342.70 = p Simplify.
The original price is $342.70.
part = percent whole

13. Answer
Need Another Example?
Rosa buys a cell phone that is on sale for
60% off. If the sale price is $79.98, what is
the original price?
$199.95

14. 1
Need Another Example?
2
3
Step-by-Step Example
Clothes Are Us and Ratcliffe’s are having sales. At Clothes Are
Us, a pair of sneakers is on sale for 40% off the regular price of
$50. At Ratcliffe’s, the same brand of sneakers is discounted
by 30% off of the regular price of $40. Which store has the
better sale price? Explain.
4.
Find the sale price of the sneakers at each store.
Clothes Are Us Ratcliffe's
60% of $50 = 0.6 $50
= $30
The sale price is $30.
70% of $40 = 0.7 $40
= $28
The sale price is $28.
Since $28 $30, the sale price at Ratcliffe's is the better buy.

15. Answer
Need Another Example?
A pair of jeans at Jeans Express is on sale
for 25% off of the original price of $35. The
same pair of jeans at Clothes Galore is on
sale for 30% off of the original price of $40.
Which store has the better sale price?
Explain.
Jeans Express;
Sample answer: $26.25 < $28

16. How did what you learned
today help you answer the
HOW can percent help you understand
situations involving money?
Course 2, Lesson 2-7
Ratios and Proportional Relationships

17. How did what you learned
today help you answer the
HOW can percent help you understand
situations involving money?
Course 2, Lesson 2-7
Ratios and Proportional Relationships
Sample answers:
• You can find things such as:
• the sale price of a DVD that normally costs $22
and is on sale for 25% off the original price
• the price of a discounted item after sales tax
is added
• the original price of cell phone with a sale price of
$239.89, which is a 30% discount

18. Write a short paragraph
that explains how
yesterday’s lesson on
sales tax and tips helped
you with today’s lesson.
Ratios and Proportional RelationshipsRatios and Proportional Relationships
Course 2, Lesson 2-7