If Fanny gives Will $39, the amount of money she has will be 30% of his. If Will gives Fanny $87, he will have the same amount of money as her. How much money did each of them have?
(a) Will
(b) Fanny

	Case 1		Case 2
	Will	Fanny	Will	Fanny
Before	10 u - 39	3 u + 39	6.5 u + 87	6.5 u - 87
Change	+ 39	- 39	- 87	+ 87
After	10 u	3 u	6.5 u	6.5 u

(a)
30% = ³⁰₁₀₀ = ³₁₀

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

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

Amount that Fanny 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 - 39 = 6.5 u + 87
10 u - 6.5 u = 87 + 39
3.5 u = 126 

1 u = 126 ÷ 3.5 = 36

Amount that Will has
= 10 u - 39
= 10 x 36 - 39
= 360 - 39
= $321 

(b)
Amount that Fanny has
= 3 u + 39
= 3 x 36 + 39
= 108 + 39
= $147

Answer(s): (a) $321; (b) $147