Sean and Archie had $108 and $90 respectively. Each of them bought a jacket and a cardigan at the same price. The cost of the jacket was 5 times as much as the cardigan. In the end, Sean had 4 times as much money as Archie. What was the difference between the cost of the cardigan and the jacket?

	Sean	Archie	Difference
Before	$108	$90	$18
Change	- 6 p	- 6 p
After	4 u	1 u	3 u

Since Sean and Archie 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 = 108 - 90
3 u = 18

1 u = 18 ÷ 3 = 6

Cost of 1 jacket = 5 p
Cost of 1 cardigan = 1 p

Total cost of 1 jacket and 1 cardigan
= 5 p + 1 p
= 6 p

6 p = 90 - 6
6 p = 84

1 p = 84 ÷ 6 = 14

Difference in the cost between the jacket and the cardigan
= 5 p - 1 p
= 4 p
= 4 x 14
= $56

Answer(s): $56