Ivory buys a skirt, a sweater, a jumpsuit and a windbreaker. The average cost of these items is $28. The total cost of the jumpsuit and the windbreaker is ³₄ of the total cost of the skirt and the sweater. If the skirt costs $12.90 and the windbreaker costs $7.60, find the difference in cost between the sweater and the jumpsuit.
Total cost of the 4 items
= 4 x 28
= $112

Total cost of the jumpsuit and the windbreaker = 3 u
Total cost of the skirt and the sweater = 4 u

Total cost of the 4 items
= 3 u + 4 u
= 7 u

7 u = 112

1 u = 112 ÷ 7 = 16

Total cost of the jumpsuit and the windbreaker
= 3 u
= 3 x 16
= $48

Cost of the jumpsuit
= 48 - 7.60
= $40.40

Total cost of the skirt and the sweater
= 4 u
= 4 x 16
= $64

Cost of the sweater
= 64 - 12.90
= $51.10

Difference in cost between the sweater and the jumpsuit
= 51.10 - 40.40
= $10.70

Answer(s): $10.70