Xylia buys a shirt, a skirt, a coat and a blazer. The average cost of these items is $36. The total cost of the coat and the blazer is ⁴₅ of the total cost of the shirt and the skirt. If the shirt costs $14.90 and the blazer costs $9.50, find the difference in cost between the skirt and the coat.
Total cost of the 4 items
= 4 x 36
= $144

Total cost of the coat and the blazer = 4 u
Total cost of the shirt and the skirt = 5 u

Total cost of the 4 items
= 4 u + 5 u
= 9 u

9 u = 144

1 u = 144 ÷ 9 = 16

Total cost of the coat and the blazer
= 4 u
= 4 x 16
= $64

Cost of the coat
= 64 - 9.50
= $54.50

Total cost of the shirt and the skirt
= 5 u
= 5 x 16
= $80

Cost of the skirt
= 80 - 14.90
= $65.10

Difference in cost between the skirt and the coat
= 65.10 - 54.50
= $10.60

Answer(s): $10.60