Xandra buys a skirt, a vest, a coat and a windbreaker. The average cost of these items is $28. The total cost of the coat and the windbreaker is ²₅ of the total cost of the skirt and the vest. If the skirt costs $15.60 and the windbreaker costs $17.80, find the difference in cost between the vest and the coat.
Total cost of the 4 items
= 4 x 28
= $112

Total cost of the coat and the windbreaker = 2 u
Total cost of the skirt and the vest = 5 u

Total cost of the 4 items
= 2 u + 5 u
= 7 u

7 u = 112

1 u = 112 ÷ 7 = 16

Total cost of the coat and the windbreaker
= 2 u
= 2 x 16
= $32

Cost of the coat
= 32 - 17.80
= $14.20

Total cost of the skirt and the vest
= 5 u
= 5 x 16
= $80

Cost of the vest
= 80 - 15.60
= $64.40

Difference in cost between the vest and the coat
= 64.40 - 14.20
= $50.20

Answer(s): $50.20