Shannon buys a shirt, a blouse, a vest and a dress. The average cost of these items is $34. The total cost of the vest and the dress is ³₅ of the total cost of the shirt and the blouse. If the shirt costs $15.70 and the dress costs $10.50, find the difference in cost between the blouse and the vest.
Total cost of the 4 items
= 4 x 34
= $136

Total cost of the vest and the dress = 3 u
Total cost of the shirt and the blouse = 5 u

Total cost of the 4 items
= 3 u + 5 u
= 8 u

8 u = 136

1 u = 136 ÷ 8 = 17

Total cost of the vest and the dress
= 3 u
= 3 x 17
= $51

Cost of the vest
= 51 - 10.50
= $40.50

Total cost of the shirt and the blouse
= 5 u
= 5 x 17
= $85

Cost of the blouse
= 85 - 15.70
= $69.30

Difference in cost between the blouse and the vest
= 69.30 - 40.50
= $28.80

Answer(s): $28.80