Gillian buys a shirt, a blouse, a skirt and a dress. The average cost of these items is $22. The total cost of the skirt and the dress is ³₅ of the total cost of the shirt and the blouse. If the shirt costs $13.30 and the dress costs $8.10, find the difference in cost between the blouse and the skirt.
Total cost of the 4 items
= 4 x 22
= $88

Total cost of the skirt and the dress = 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 = 88

1 u = 88 ÷ 8 = 11

Total cost of the skirt and the dress
= 3 u
= 3 x 11
= $33

Cost of the skirt
= 33 - 8.10
= $24.90

Total cost of the shirt and the blouse
= 5 u
= 5 x 11
= $55

Cost of the blouse
= 55 - 13.30
= $41.70

Difference in cost between the blouse and the skirt
= 41.70 - 24.90
= $16.80

Answer(s): $16.80