Tammy buys a jacket, a windbreaker, a blazer and a sweater. The average cost of these items is $45. The total cost of the blazer and the sweater is ⁴₅ of the total cost of the jacket and the windbreaker. If the jacket costs $10.90 and the sweater costs $14.40, find the difference in cost between the windbreaker and the blazer.
Total cost of the 4 items
= 4 x 45
= $180

Total cost of the blazer and the sweater = 4 u
Total cost of the jacket and the windbreaker = 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 blazer and the sweater
= 4 u
= 4 x 20
= $80

Cost of the blazer
= 80 - 14.40
= $65.60

Total cost of the jacket and the windbreaker
= 5 u
= 5 x 20
= $100

Cost of the windbreaker
= 100 - 10.90
= $89.10

Difference in cost between the windbreaker and the blazer
= 89.10 - 65.60
= $23.50

Answer(s): $23.50