Ivory buys a blouse, a dress, a coat and a jumpsuit. The average cost of these items is $45. The total cost of the coat and the jumpsuit is ⁴₅ of the total cost of the blouse and the dress. If the blouse costs $13.80 and the jumpsuit costs $16.30, find the difference in cost between the dress and the coat.
Total cost of the 4 items
= 4 x 45
= $180

Total cost of the coat and the jumpsuit = 4 u
Total cost of the blouse and the dress = 5 u

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

9 u = 180

1 u = 180 ÷ 9 = 20

Total cost of the coat and the jumpsuit
= 4 u
= 4 x 20
= $80

Cost of the coat
= 80 - 16.30
= $63.70

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

Cost of the dress
= 100 - 13.80
= $86.20

Difference in cost between the dress and the coat
= 86.20 - 63.70
= $22.50

Answer(s): $22.50