Warren had $330 and Justin had $122 at first. Each of them bought an identical sweater and an identical windbreaker from the same shop. The windbreaker cost 2 times as much as the sweater. In the end, Warren had 3 times as much money as Justin. What was the cost of the sweater?

	Warren	Justin	Difference
Before	$330	$122	$208
Change	- 1 sweater - 1 windbreaker	- 1 sweater - 1 windbreaker
After	3 u	1 u	2 u

Since Warren and Justin bought the same items, the difference  in their amounts remains the same.

Difference in the amounts that they had
= 3 u - 1 u
= 2 u

2 u = 330 - 122
2 u = 208

1 u = 208 ÷ 2 = 104

Amount that Justin had in the end
= 1 u
= $104

Cost of 1 sweater and 1 windbreaker
= 122 - 1 u
= 122 - 104
= $18

The windbreaker cost 2 times as much as the sweater.

Cost of 1 sweater = 1 p
Cost of 1 windbreaker = 2 p

Total cost of 1 sweater and 1 windbreaker
= 1 p + 2 p
= 3 p

3 p = 18

1 p = 18 ÷ 3 = 6

Cost of the sweater
= 1 p
= $6

Answer(s): $6