If Yoko gives Glen $21, the amount of money she has will be 80% of his. If Glen gives Yoko $1, he will have the same amount of money as her. How much money did each of them have?
(a) Glen
(b) Yoko

	Case 1		Case 2
	Glen	Yoko	Glen	Yoko
Before	5 u - 21	4 u + 21	4.5 u + 1	4.5 u - 1
Change	+ 21	- 21	- 1	+ 1
After	5 u	4 u	4.5 u	4.5 u

(a)
80% = ⁸⁰₁₀₀ = ⁴₅

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

In Case 2, when Glen gives to Yoko, there is an internal transfer of money from Glen to Yoko. 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 Yoko and Glen have
= 5 u + 4 u
= 9 u

Amount that Yoko and Glen each has in the end for Case 2
= 9 u ÷ 2
= 4.5 u

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

5 u - 21 = 4.5 u + 1
5 u - 4.5 u = 1 + 21
0.5 u = 22 

1 u = 22 ÷ 0.5 = 44

Amount that Glen has
= 5 u - 21
= 5 x 44 - 21
= 220 - 21
= $199 

(b)
Amount that Yoko has
= 4 u + 21
= 4 x 44 + 21
= 176 + 21
= $197

Answer(s): (a) $199; (b) $197