Eric buys a dress, a windbreaker and a blouse. The average cost of these items is $36. The cost of the blouse is four times the total cost of the dress and the windbreaker. If the dress costs $14, find the difference in cost between the windbreaker and the blouse.
Total cost of the 3 items
= 3 x 36
= $108

Total cost of the dress and the windbreaker = 1 u
Cost of the blouse = 4 u

Total cost of the 3 items 
= 1 u + 4 u
= 5 u

5 u = 108 

1 u = 108 ÷ 5 = 21.60

Total cost of the dress and the windbreaker = $21.60

Cost of the windbreaker 
= 21.60 - 14
= $7.60

Cost of the blouse
= 4 u
= 4 x 21.60
= $86.40

Difference in cost between the windbreaker and the blouse
= 86.40 - 7.60
= $78.80

Answer(s): $78.80