Min buys a jacket, a sweater, a windbreaker and a vest. The average cost of these items is $20. The total cost of the windbreaker and the vest is ³₅ of the total cost of the jacket and the sweater. If the jacket costs $13.30 and the vest costs $7.70, find the difference in cost between the sweater and the windbreaker.
Total cost of the 4 items
= 4 x 20
= $80

Total cost of the windbreaker and the vest = 3 u
Total cost of the jacket and the sweater = 5 u

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

8 u = 80

1 u = 80 ÷ 8 = 10

Total cost of the windbreaker and the vest
= 3 u
= 3 x 10
= $30

Cost of the windbreaker
= 30 - 7.70
= $22.30

Total cost of the jacket and the sweater
= 5 u
= 5 x 10
= $50

Cost of the sweater
= 50 - 13.30
= $36.70

Difference in cost between the sweater and the windbreaker
= 36.70 - 22.30
= $14.40

Answer(s): $14.40