Gillian buys a shirt, a blouse, a jacket and a coat. The average cost of these items is $20. The total cost of the jacket and the coat is ³₅ of the total cost of the shirt and the blouse. If the shirt costs $16.40 and the coat costs $16.60, find the difference in cost between the blouse and the jacket.
Total cost of the 4 items
= 4 x 20
= $80

Total cost of the jacket and the coat = 3 u
Total cost of the shirt and the blouse = 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 jacket and the coat
= 3 u
= 3 x 10
= $30

Cost of the jacket
= 30 - 16.60
= $13.40

Total cost of the shirt and the blouse
= 5 u
= 5 x 10
= $50

Cost of the blouse
= 50 - 16.40
= $33.60

Difference in cost between the blouse and the jacket
= 33.60 - 13.40
= $20.20

Answer(s): $20.20