Emma buys a skirt, a blazer, a shirt and a dress. The average cost of these items is $25. The total cost of the shirt and the dress is ²₃ of the total cost of the skirt and the blazer. If the skirt costs $10.60 and the dress costs $9.30, find the difference in cost between the blazer and the shirt.
Total cost of the 4 items
= 4 x 25
= $100

Total cost of the shirt and the dress = 2 u
Total cost of the skirt and the blazer = 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 shirt and the dress
= 2 u
= 2 x 20
= $40

Cost of the shirt
= 40 - 9.30
= $30.70

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

Cost of the blazer
= 60 - 10.60
= $49.40

Difference in cost between the blazer and the shirt
= 49.40 - 30.70
= $18.70

Answer(s): $18.70