Natalie buys a blazer, a dress, a coat and a windbreaker. The average cost of these items is $25. The total cost of the coat and the windbreaker is ²₃ of the total cost of the blazer and the dress. If the blazer costs $16.90 and the windbreaker costs $6.20, find the difference in cost between the dress and the coat.
Total cost of the 4 items
= 4 x 25
= $100

Total cost of the coat and the windbreaker = 2 u
Total cost of the blazer and the dress = 3 u

Total cost of the 4 items
= 2 u + 3 u
= 5 u

5 u = 100

1 u = 100 ÷ 5 = 20

Total cost of the coat and the windbreaker
= 2 u
= 2 x 20
= $40

Cost of the coat
= 40 - 6.20
= $33.80

Total cost of the blazer and the dress
= 3 u
= 3 x 20
= $60

Cost of the dress
= 60 - 16.90
= $43.10

Difference in cost between the dress and the coat
= 43.10 - 33.80
= $9.30

Answer(s): $9.30