Cathy buys a vest, a dress, a skirt and a blazer. The average cost of these items is $27. The total cost of the skirt and the blazer is ⁴₅ of the total cost of the vest and the dress. If the vest costs $13.60 and the blazer costs $14.30, find the difference in cost between the dress and the skirt.
Total cost of the 4 items
= 4 x 27
= $108

Total cost of the skirt and the blazer = 4 u
Total cost of the vest and the dress = 5 u

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

9 u = 108

1 u = 108 ÷ 9 = 12

Total cost of the skirt and the blazer
= 4 u
= 4 x 12
= $48

Cost of the skirt
= 48 - 14.30
= $33.70

Total cost of the vest and the dress
= 5 u
= 5 x 12
= $60

Cost of the dress
= 60 - 13.60
= $46.40

Difference in cost between the dress and the skirt
= 46.40 - 33.70
= $12.70

Answer(s): $12.70