Perry and Fred had $80 and $60 respectively. Each of them bought a skirt and a blouse at the same price. The cost of the skirt was 4 times as much as the blouse. In the end, Perry had 3 times as much money as Fred. What was the difference between the cost of the blouse and the skirt?

	Perry	Fred	Difference
Before	$80	$60	$20
Change	- 5 p	- 5 p
After	3 u	1 u	2 u

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

3 u - 1 u = 80 - 60
2 u = 20

1 u = 20 ÷ 2 = 10

Cost of 1 skirt = 4 p
Cost of 1 blouse = 1 p

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

5 p = 60 - 10
5 p = 50

1 p = 50 ÷ 5 = 10

Difference in the cost between the skirt and the blouse
= 4 p - 1 p
= 3 p
= 3 x 10
= $30

Answer(s): $30