Jean buys a sweater, a dress, a blouse and a shirt. The average cost of these items is $35. The total cost of the blouse and the shirt is ²₅ of the total cost of the sweater and the dress. If the sweater costs $11.30 and the shirt costs $16.90, find the difference in cost between the dress and the blouse.
Total cost of the 4 items
= 4 x 35
= $140

Total cost of the blouse and the shirt = 2 u
Total cost of the sweater and the dress = 5 u

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

7 u = 140

1 u = 140 ÷ 7 = 20

Total cost of the blouse and the shirt
= 2 u
= 2 x 20
= $40

Cost of the blouse
= 40 - 16.90
= $23.10

Total cost of the sweater and the dress
= 5 u
= 5 x 20
= $100

Cost of the dress
= 100 - 11.30
= $88.70

Difference in cost between the dress and the blouse
= 88.70 - 23.10
= $65.60

Answer(s): $65.60