Erika buys a jacket, a dress, a sweater and a skirt. The average cost of these items is $34. The total cost of the sweater and the skirt is ³₅ of the total cost of the jacket and the dress. If the jacket costs $19.10 and the skirt costs $12.20, find the difference in cost between the dress and the sweater.
Total cost of the 4 items
= 4 x 34
= $136

Total cost of the sweater and the skirt = 3 u
Total cost of the jacket and the dress = 5 u

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

8 u = 136

1 u = 136 ÷ 8 = 17

Total cost of the sweater and the skirt
= 3 u
= 3 x 17
= $51

Cost of the sweater
= 51 - 12.20
= $38.80

Total cost of the jacket and the dress
= 5 u
= 5 x 17
= $85

Cost of the dress
= 85 - 19.10
= $65.90

Difference in cost between the dress and the sweater
= 65.90 - 38.80
= $27.10

Answer(s): $27.10