If Marion gives Ian $24, the amount of money she has will be 25% of his. If Ian gives Marion $48, he will have the same amount of money as her. How much money did each of them have?
(a) Ian
(b) Marion

	Case 1		Case 2
	Ian	Marion	Ian	Marion
Before	4 u - 24	1 u + 24	2.5 u + 48	2.5 u - 48
Change	+ 24	- 24	- 48	+ 48
After	4 u	1 u	2.5 u	2.5 u

(a)
25% = ²⁵₁₀₀ = ¹₄

In Case 1, when Marion gives to Ian, there is an internal transfer of money from Marion to Ian.  The total amount that both have remains the same.

In Case 2, when Ian gives to Marion, there is an internal transfer of money from Ian to Marion. The total amount that both have remains the same.

The total amount that both have in Case 1 and Case 2 are the same.

Total amount that Marion and Ian have
= 4 u + 1 u
= 5 u

Amount that Marion and Ian each has in the end for Case 2
= 5 u ÷ 2
= 2.5 u

Amount that Ian has at first is the same in Case 1 and Case 2.

4 u - 24 = 2.5 u + 48
4 u - 2.5 u = 48 + 24
1.5 u = 72 

1 u = 72 ÷ 1.5 = 48

Amount that Ian has
= 4 u - 24
= 4 x 48 - 24
= 192 - 24
= $168 

(b)
Amount that Marion has
= 1 u + 24
= 1 x 48 + 24
= 48 + 24
= $72

Answer(s): (a) $168; (b) $72