Luke had $279 and Will had $173 at first. Each of them bought an identical skirt and an identical blazer from the same shop. The blazer cost 4 times as much as the skirt. In the end, Luke had 3 times as much money as Will. What was the cost of the skirt?

	Luke	Will	Difference
Before	$279	$173	$106
Change	- 1 skirt - 1 blazer	- 1 skirt - 1 blazer
After	3 u	1 u	2 u

Since Luke and Will 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 = 279 - 173
2 u = 106

1 u = 106 ÷ 2 = 53

Amount that Will had in the end
= 1 u
= $53

Cost of 1 skirt and 1 blazer
= 173 - 1 u
= 173 - 53
= $120

The blazer cost 4 times as much as the skirt.

Cost of 1 skirt = 1 p
Cost of 1 blazer = 4 p

Total cost of 1 skirt and 1 blazer
= 1 p + 4 p
= 5 p

5 p = 120

1 p = 120 ÷ 5 = 24

Cost of the skirt
= 1 p
= $24

Answer(s): $24