If Risa gives Will $38, the amount of money she has will be 30% of his. If Will gives Risa $102, he will have the same amount of money as her. How much money did each of them have?
(a) Will
(b) Risa

	Case 1		Case 2
	Will	Risa	Will	Risa
Before	10 u - 38	3 u + 38	6.5 u + 102	6.5 u - 102
Change	+ 38	- 38	- 102	+ 102
After	10 u	3 u	6.5 u	6.5 u

(a)
30% = ³⁰₁₀₀ = ³₁₀

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

In Case 2, when Will gives to Risa, there is an internal transfer of money from Will to Risa. 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 Risa and Will have
= 10 u + 3 u
= 13 u

Amount that Risa and Will each has in the end for Case 2
= 13 u ÷ 2
= 6.5 u

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

10 u - 38 = 6.5 u + 102
10 u - 6.5 u = 102 + 38
3.5 u = 140 

1 u = 140 ÷ 3.5 = 40

Amount that Will has
= 10 u - 38
= 10 x 40 - 38
= 400 - 38
= $362 

(b)
Amount that Risa has
= 3 u + 38
= 3 x 40 + 38
= 120 + 38
= $158

Answer(s): (a) $362; (b) $158