If Risa gives Pierre $35, the amount of money she has will be 40% of his. If Pierre gives Risa $28, he will have the same amount of money as her. How much money did each of them have?
(a) Pierre
(b) Risa

	Case 1		Case 2
	Pierre	Risa	Pierre	Risa
Before	5 u - 35	2 u + 35	3.5 u + 28	3.5 u - 28
Change	+ 35	- 35	- 28	+ 28
After	5 u	2 u	3.5 u	3.5 u

(a)
40% = ⁴⁰₁₀₀ = ²₅

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

In Case 2, when Pierre gives to Risa, there is an internal transfer of money from Pierre 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 Pierre have
= 5 u + 2 u
= 7 u

Amount that Risa and Pierre each has in the end for Case 2
= 7 u ÷ 2
= 3.5 u

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

5 u - 35 = 3.5 u + 28
5 u - 3.5 u = 28 + 35
1.5 u = 63 

1 u = 63 ÷ 1.5 = 42

Amount that Pierre has
= 5 u - 35
= 5 x 42 - 35
= 210 - 35
= $175 

(b)
Amount that Risa has
= 2 u + 35
= 2 x 42 + 35
= 84 + 35
= $119

Answer(s): (a) $175; (b) $119