If Dana gives Albert $39, the amount of money she has will be 25% of his. If Albert gives Dana $9, he will have the same amount of money as her. How much money did each of them have?
(a) Albert
(b) Dana

	Case 1		Case 2
	Albert	Dana	Albert	Dana
Before	4 u - 39	1 u + 39	2.5 u + 9	2.5 u - 9
Change	+ 39	- 39	- 9	+ 9
After	4 u	1 u	2.5 u	2.5 u

(a)
25% = ²⁵₁₀₀ = ¹₄

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

In Case 2, when Albert gives to Dana, there is an internal transfer of money from Albert to Dana. 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 Dana and Albert have
= 4 u + 1 u
= 5 u

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

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

4 u - 39 = 2.5 u + 9
4 u - 2.5 u = 9 + 39
1.5 u = 48 

1 u = 48 ÷ 1.5 = 32

Amount that Albert has
= 4 u - 39
= 4 x 32 - 39
= 128 - 39
= $89 

(b)
Amount that Dana has
= 1 u + 39
= 1 x 32 + 39
= 32 + 39
= $71

Answer(s): (a) $89; (b) $71