Ahmad had $220 and Nick had $124 at first. Each of them bought an identical cardigan and an identical shirt from the same shop. The shirt cost 4 times as much as the cardigan. In the end, Ahmad had 5 times as much money as Nick. What was the cost of the cardigan?

	Ahmad	Nick	Difference
Before	$220	$124	$96
Change	- 1 cardigan - 1 shirt	- 1 cardigan - 1 shirt
After	5 u	1 u	4 u

Since Ahmad and Nick bought the same items, the difference  in their amounts remains the same.

Difference in the amounts that they had
= 5 u - 1 u
= 4 u

4 u = 220 - 124
4 u = 96

1 u = 96 ÷ 4 = 24

Amount that Nick had in the end
= 1 u
= $24

Cost of 1 cardigan and 1 shirt
= 124 - 1 u
= 124 - 24
= $100

The shirt cost 4 times as much as the cardigan.

Cost of 1 cardigan = 1 p
Cost of 1 shirt = 4 p

Total cost of 1 cardigan and 1 shirt
= 1 p + 4 p
= 5 p

5 p = 100

1 p = 100 ÷ 5 = 20

Cost of the cardigan
= 1 p
= $20

Answer(s): $20