Xuan buys a blazer, a sweater, a jacket and a windbreaker. The average cost of these items is $28. The total cost of the jacket and the windbreaker is ²₅ of the total cost of the blazer and the sweater. If the blazer costs $19.40 and the windbreaker costs $15.10, find the difference in cost between the sweater and the jacket.
Total cost of the 4 items
= 4 x 28
= $112

Total cost of the jacket and the windbreaker = 2 u
Total cost of the blazer and the sweater = 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 jacket and the windbreaker
= 2 u
= 2 x 16
= $32

Cost of the jacket
= 32 - 15.10
= $16.90

Total cost of the blazer and the sweater
= 5 u
= 5 x 16
= $80

Cost of the sweater
= 80 - 19.40
= $60.60

Difference in cost between the sweater and the jacket
= 60.60 - 16.90
= $43.70

Answer(s): $43.70