If Sabrina gives Japheth $20, the amount of money she has will be 10% of his. If Japheth gives Sabrina $187, he will have the same amount of money as her. How much money did each of them have?
(a) Japheth
(b) Sabrina

	Case 1		Case 2
	Japheth	Sabrina	Japheth	Sabrina
Before	10 u - 20	1 u + 20	5.5 u + 187	5.5 u - 187
Change	+ 20	- 20	- 187	+ 187
After	10 u	1 u	5.5 u	5.5 u

(a)
10% = ¹⁰₁₀₀ = ¹₁₀

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

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

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

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

10 u - 20 = 5.5 u + 187
10 u - 5.5 u = 187 + 20
4.5 u = 207 

1 u = 207 ÷ 4.5 = 46

Amount that Japheth has
= 10 u - 20
= 10 x 46 - 20
= 460 - 20
= $440 

(b)
Amount that Sabrina has
= 1 u + 20
= 1 x 46 + 20
= 46 + 20
= $66

Answer(s): (a) $440; (b) $66