Zara buys a shirt, a sweater, a blazer and a vest. The average cost of these items is $36. The total cost of the blazer and the vest is ³₅ of the total cost of the shirt and the sweater. If the shirt costs $17.60 and the vest costs $9.20, find the difference in cost between the sweater and the blazer.
Total cost of the 4 items
= 4 x 36
= $144

Total cost of the blazer and the vest = 3 u
Total cost of the shirt and the sweater = 5 u

Total cost of the 4 items
= 3 u + 5 u
= 8 u

8 u = 144

1 u = 144 ÷ 8 = 18

Total cost of the blazer and the vest
= 3 u
= 3 x 18
= $54

Cost of the blazer
= 54 - 9.20
= $44.80

Total cost of the shirt and the sweater
= 5 u
= 5 x 18
= $90

Cost of the sweater
= 90 - 17.60
= $72.40

Difference in cost between the sweater and the blazer
= 72.40 - 44.80
= $27.60

Answer(s): $27.60