Opal buys a blouse, a vest, a dress and a windbreaker. The average cost of these items is $28. The total cost of the dress and the windbreaker is ²₅ of the total cost of the blouse and the vest. If the blouse costs $19.40 and the windbreaker costs $12.50, find the difference in cost between the vest and the dress.
Total cost of the 4 items
= 4 x 28
= $112

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

Cost of the dress
= 32 - 12.50
= $19.50

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

Cost of the vest
= 80 - 19.40
= $60.60

Difference in cost between the vest and the dress
= 60.60 - 19.50
= $41.10

Answer(s): $41.10