Julie buys a shirt, a coat, a blazer and a jacket. The average cost of these items is $55. The total cost of the blazer and the jacket is ⁵₆ of the total cost of the shirt and the coat. If the shirt costs $10.30 and the jacket costs $9.60, find the difference in cost between the coat and the blazer.
Total cost of the 4 items
= 4 x 55
= $220

Total cost of the blazer and the jacket = 5 u
Total cost of the shirt and the coat = 6 u

Total cost of the 4 items
= 5 u + 6 u
= 11 u

11 u = 220

1 u = 220 ÷ 11 = 20

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

Cost of the blazer
= 100 - 9.60
= $90.40

Total cost of the shirt and the coat
= 6 u
= 6 x 20
= $120

Cost of the coat
= 120 - 10.30
= $109.70

Difference in cost between the coat and the blazer
= 109.70 - 90.40
= $19.30

Answer(s): $19.30