Lynn buys a windbreaker, a sweater, a blazer and a shirt. The average cost of these items is $35. The total cost of the blazer and the shirt is ³₄ of the total cost of the windbreaker and the sweater. If the windbreaker costs $10.50 and the shirt costs $10.60, find the difference in cost between the sweater and the blazer.
Total cost of the 4 items
= 4 x 35
= $140

Total cost of the blazer and the shirt = 3 u
Total cost of the windbreaker and the sweater = 4 u

Total cost of the 4 items
= 3 u + 4 u
= 7 u

7 u = 140

1 u = 140 ÷ 7 = 20

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

Cost of the blazer
= 60 - 10.60
= $49.40

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

Cost of the sweater
= 80 - 10.50
= $69.50

Difference in cost between the sweater and the blazer
= 69.50 - 49.40
= $20.10

Answer(s): $20.10