If Winnie gives Eric $37, the amount of money she has will be 10% of his. If Eric gives Winnie $170, he will have the same amount of money as her. How much money did each of them have?
(a) Eric
(b) Winnie

	Case 1		Case 2
	Eric	Winnie	Eric	Winnie
Before	10 u - 37	1 u + 37	5.5 u + 170	5.5 u - 170
Change	+ 37	- 37	- 170	+ 170
After	10 u	1 u	5.5 u	5.5 u

(a)
10% = ¹⁰₁₀₀ = ¹₁₀

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

In Case 2, when Eric gives to Winnie, there is an internal transfer of money from Eric to Winnie. 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 Winnie and Eric have
= 10 u + 1 u
= 11 u

Amount that Winnie and Eric each has in the end for Case 2
= 11 u ÷ 2
= 5.5 u

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

10 u - 37 = 5.5 u + 170
10 u - 5.5 u = 170 + 37
4.5 u = 207 

1 u = 207 ÷ 4.5 = 46

Amount that Eric has
= 10 u - 37
= 10 x 46 - 37
= 460 - 37
= $423 

(b)
Amount that Winnie has
= 1 u + 37
= 1 x 46 + 37
= 46 + 37
= $83

Answer(s): (a) $423; (b) $83