Lesson 12: Practice Problems

Problem 1 From Unit 4 Lesson 12

A backpack normally costs $25 but it is on sale for $21. What percentage is the discount?

Problem 2 From Unit 5 Lesson 9

Find each product.

$\frac{2}{5} \cdot (- 10)$
$- 8 \cdot (\frac{- 3}{2})$
$\frac{10}{6} \cdot 0.6$
$(\frac{- 100}{37}) \cdot (- 0.37)$

Problem 3

Select all expressions that show $x$ increased by 35%.

$1.35 x$
$\frac{35}{100} x$
$x + \frac{35}{100} x$
$(1 + 0.35) x$
$\frac{100 + 35}{100} x$
$(100 + 35) x$

Problem 4 From Unit 4 Lesson 11

Complete each sentence with the word discount, deposit, or withdrawal.

Clare took $20 out of her bank account. She made a .
Kiran used a coupon when he bought a pair of shoes. He got a .
Priya put $20 into her bank account. She made a .
Lin paid less than usual for a pack of gum because it was on sale. She got a .

Problem 5

Here are two stories:

The initial freshman class at a college is 10% smaller than last year’s class. But then during the first week of classes, 20 more students enroll. There are then 830 students in the freshman class.
A store reduces the price of a computer by $20. Then during a 10% off sale, a customer pays $830.

Here are two equations:

$0.9 x + 20 = 830$
$0.9 (x - 20) = 830$

Decide which equation represents each story.
Explain why one equation has parentheses and the other doesn’t.
Solve each equation, and explain what the solution means in the situation.