Justin buys a windbreaker, a vest and a sweater. The average cost of these items is $52. The cost of the sweater is four times the total cost of the windbreaker and the vest. If the windbreaker costs $12, find the difference in cost between the vest and the sweater.
Total cost of the 3 items
= 3 x 52
= $156

Total cost of the windbreaker and the vest = 1 u
Cost of the sweater = 4 u

Total cost of the 3 items 
= 1 u + 4 u
= 5 u

5 u = 156 

1 u = 156 ÷ 5 = 31.20

Total cost of the windbreaker and the vest = $31.20

Cost of the vest 
= 31.20 - 12
= $19.20

Cost of the sweater
= 4 u
= 4 x 31.20
= $124.80

Difference in cost between the vest and the sweater
= 124.80 - 19.20
= $105.60

Answer(s): $105.60