Will and Riordan had $156 and $102 respectively. Each of them bought a hoodie and a cardigan at the same price. The cost of the hoodie was 3 times as much as the cardigan. In the end, Will had 4 times as much money as Riordan. What was the difference between the cost of the cardigan and the hoodie?

	Will	Riordan	Difference
Before	$156	$102	$54
Change	- 4 p	- 4 p
After	4 u	1 u	3 u

Since Will and Riordan bought the same items at the same price, the difference in the amounts they had remains unchanged at first and in the end.

4 u - 1 u = 156 - 102
3 u = 54

1 u = 54 ÷ 3 = 18

Cost of 1 hoodie = 3 p
Cost of 1 cardigan = 1 p

Total cost of 1 hoodie and 1 cardigan
= 3 p + 1 p
= 4 p

4 p = 102 - 18
4 p = 84

1 p = 84 ÷ 4 = 21

Difference in the cost between the hoodie and the cardigan
= 3 p - 1 p
= 2 p
= 2 x 21
= $42

Answer(s): $42