Cathy buys a jacket, a skirt, a blazer and a coat. The average cost of these items is $20. The total cost of the blazer and the coat is ³₅ of the total cost of the jacket and the skirt. If the jacket costs $18.20 and the coat costs $9.80, find the difference in cost between the skirt and the blazer.
Total cost of the 4 items
= 4 x 20
= $80

Total cost of the blazer and the coat = 3 u
Total cost of the jacket and the skirt = 5 u

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

8 u = 80

1 u = 80 ÷ 8 = 10

Total cost of the blazer and the coat
= 3 u
= 3 x 10
= $30

Cost of the blazer
= 30 - 9.80
= $20.20

Total cost of the jacket and the skirt
= 5 u
= 5 x 10
= $50

Cost of the skirt
= 50 - 18.20
= $31.80

Difference in cost between the skirt and the blazer
= 31.80 - 20.20
= $11.60

Answer(s): $11.60