Three girls are selling cases of popcorn to earn money for a band trip. in week 1, emily sold 2 3/4 cases, brenda sold 4 1/4 cases, and shannon sold 3 1/2 cases.

part a
how many cases of popcorn have the girls sold in all? (use associative property) explain how you found the answer.
part b
the girls must sell a total of 35 cases in order to have enough money for the trip. suppose they sell the same amount in week 2 and week 3 of the sale as in week 1. will the girls have sold enough cases of popcorn to go on the trip? explain.

Given:
Week 1:
Emily = 2 3/4 cases
Brenda = 4 1/4 cases
Shannon = 3 1/2 cases

Convert these mixed fractions into improper fractions:
2 3/4 = ((2*4)+3)/4 = 11/4
4 1/4 = ((4*4)+1)/4 = 17/4
3 1/2 = ((3*2)+1)/2 =   7/2

7/2 must be multiplied by a fraction to have a denominator of 4.
7/2 * 2/2 = 7*2 / 2*2 = 14/4

11/4 + 17/4 + 14/4 = (11+17+14)/4 = 42/4 = 10 2/4 or 10 1/2 cases

Same sales on week 2 and 3.

42/4 x 3 weeks = (42*3)/4 = 126/4 = 31 2/4 or 31 1/2 cases

The were not able to sell the 35 cases needed to go on the trip. They needed to sell 3 1/2 cases more.

35 - 31 1/2 = 3 1/2