1. Write and Solve Proportions
SWBAT write proportions ; use the cross-products rule to determine whether ratios form a proportion; find the missing term in a proportion

2. Discuss- how would you solve this?
Miss Brougham uses 9 gallons of gas when she drives 225 miles on the highway. Mrs. Fazio used 7 gallons of gas when she drives 175 miles on the highway. Is the average number of miles per gallon of gas the same for Miss Brougham’s car as for Mrs. Fazio’s?

3. Definitions Proportion Cross-Products Rule
An equation stating that two ratios are equivalent
Cross-Products Rule
In a proportion the product of the means is the same as the product of the extremes
a:b = c:d
extremes
means

4. Examples 6/12 and 10/18 6/36 and 6/1 4 ½ to 9 and 2/5 to 4/5

5. Examples 5/6 = n/48 9/t = 36/8 0.9/3.6 = 1.2/y 2/3 = x/15 = 8/y
52/a = 10/20 = b/350

6. Try These Are they equivalent: Solve: 8:15 and 20:45
8 x 45 and 15 x 20
360 and 300
No they are not a proportion
Solve:
n/16 = 18/32
32n = 16 x 18
32n = 288
n = 9