Xavier had $263 and Bryan had $137 at first. Each of them bought an identical shirt and an identical windbreaker from the same shop. The windbreaker cost 4 times as much as the shirt. In the end, Xavier had 4 times as much money as Bryan. What was the cost of the shirt?

	Xavier	Bryan	Difference
Before	$263	$137	$126
Change	- 1 shirt - 1 windbreaker	- 1 shirt - 1 windbreaker
After	4 u	1 u	3 u

Since Xavier and Bryan bought the same items, the difference  in their amounts remains the same.

Difference in the amounts that they had
= 4 u - 1 u
= 3 u

3 u = 263 - 137
3 u = 126

1 u = 126 ÷ 3 = 42

Amount that Bryan had in the end
= 1 u
= $42

Cost of 1 shirt and 1 windbreaker
= 137 - 1 u
= 137 - 42
= $95

The windbreaker cost 4 times as much as the shirt.

Cost of 1 shirt = 1 p
Cost of 1 windbreaker = 4 p

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

5 p = 95

1 p = 95 ÷ 5 = 19

Cost of the shirt
= 1 p
= $19

Answer(s): $19