1. Problem of the Day
The last time you bought pizza, 3 pizzas were enough to feed 7 people. At that rate, how many pizzas should you buy for a party for 35 people?
Find each unit cost and determine which item is the better buy.
5 towels for $39 or 7 towels for $46

2. Problem of the Day
The last time you bought pizza, 3 pizzas were enough to feed 7 people. At that rate, how many pizzas should you buy for a party for 35 people?
You should buy 15 pizzas.
Find each unit cost and determine which item is the better buy.
5 towels for $39 or 7 towels for $46
$7.80 $6.57
The 7-towel price is the better buy.

3. A proportion is an equation stating that two ratios are equal.
Proportions
LESSON 5-3
What is Proportion
A proportion is an equation stating that two ratios are equal.
There are three ways to determine whether a pair of ratios form a proportion.
Write in simplest form
Find common multiplier between numerator and denominator
Find cross-products and check for equality
5-3

4. Determine if the ratios can form a proportion.
Proportions
LESSON 5-3
Additional Examples
Quick Check
Determine if the ratios can form a proportion. 42 56 , 64 42 56
Divide 42 and 56 by their GCF, which is 14. = 3 4 42 56
÷ 14 56 64
Divide 56 and 64 by their GCF, which is 8. = 7 8 56 64
÷ 8
The ratios in simplest form are not equal. They cannot form a proportion.
5-3

5.  9  8  6 Determine if the ratios can form a proportion. , a. b.
Proportions
LESSON 5-3
Additional Examples
Determine if the ratios can form a proportion. 2 3 18 24 , a. 5 4 30 b.
 9
 8
 6 2 3 18 24 5 4 30 24
and cannot
form a proportion.
They don’t have a
common multiplier. 2 3 18 24
and can form a proportion. 5 4 30 24
Quick Check
5-3

6. Determine if the ratios can form a proportion.
Proportions
LESSON 5-3
Additional Examples
Determine if the ratios can form a proportion. 8 6 9 7 , b. a. 4 10 15 4 10 6 15
Test the pair of ratios. 8 6 9 7
4 • • 6
Write cross products.
8 • • 9
60 = 60
Simplify. = /
Yes, and form a proportion. 4 10 6 15
No, and do not form a proportion. 8 6 9 7
Quick Check
5-3

7. Determine if the ratios can form a proportion. 1. , 2. , 3. , 4. ,
Proportions
LESSON 5-3
Lesson Quiz
Determine if the ratios can form a proportion.
, , , , 35 56 45 63 18 26 9 13 12 16 30 no
yes
yes no
Now, start on the worksheet: Puzzle and Enrichment 5-3
5-3