1. Lesson 2-7
Percent of Change

2. The Essential Question
Why is it important to be able to express algebraic expressions in different way?
Answer:

3. A short review Are 17 34 and 3 12 equivalent ratios?
Solve = 35 𝑥 .
Solve .6 𝑏 =
Solve = 𝑧 5

4. More Review
A bottling machine can fill 210 bottles every 5 minutes. How many bottles can it fill in 1 hour?
The table shows the prices of three different sizes of detergent. Which size has the lowest price per ounce?
Bottle
Size
Full
Price
Price per ounce 21
$4.58 54
$10.28 96
$19.29
The _________ oz is the best buy.

5. Objective: Find the percent of change
Solve problems involving percent of change
Vocabulary:
Percent of change
Percent of increase
Percent of decrease

6. Some examples and practice:
Determine whether the percent of change is a percent of increase of a percent of decrease. Then find the percent of change.
Original: 20
New: 4
The amount of change is:
This is a percent of ____________ because the new amount is __________
Than the original amount.
Find the percent of change.
New: 18
Determine whether the percent of change is a percent of increase or a percent of decrease. Then find the percent of change.
Original: 12
New: 48

7. Percent of Change 𝐶ℎ𝑎𝑛𝑔𝑒 𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 𝑎𝑚𝑡 Change to percent
Determine whether the percent of change is a percent of increase or a percent of decrease Then find the percent of change.
Original: 32
New: 40
Find the amount of change. Since the new amount is __________ than the original, the percent of change is the percent of __________.
Find the percent using the original number, 32, as the base.
𝐶ℎ𝑎𝑛𝑔𝑒 𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 𝑎𝑚𝑡 Change to percent

8. Let s = the selling price of the book
Real World Problem:
The price a used-book store pays to buy a book is $5. The store sells the book for 28% above the price that it pays for the book. What is the selling price of the book?
Let s = the selling price of the book
Change
Percent of change
Bookstore cost
100 percent

9. More Real World Examples
SALES At one store the price of a pair of jeans is $26.oo. At another store the same pair of jeans has a price that is 22% higher. What is the price of jeans at the second store?
Sales Tax A meal for two at a restaurant costs $ If the
sales tax is 5%, what is the total price of the meal?

10. More Applications
A portable CD player costs $ If the sales tax is 6.75% what is the total price of the CD player?
DISCOUNT A dog toy is on sale for 20% off the original price. If the original price of the toy is $3.80, what is the discounted price?

11. Check your progress…
A baseball cap is on sale for 15% off the original price. I the original price of the cap is $19.99, what is the discounted price?

12. Activities for the rest of the day
Mid-chapter quiz
When your quiz is complete, work on your homework, quietly