If Nicole gives Oscar $15, the amount of money she has will be 80% of his. If Oscar gives Nicole $7, he will have the same amount of money as her. How much money did each of them have?
(a) Oscar
(b) Nicole

	Case 1		Case 2
	Oscar	Nicole	Oscar	Nicole
Before	5 u - 15	4 u + 15	4.5 u + 7	4.5 u - 7
Change	+ 15	- 15	- 7	+ 7
After	5 u	4 u	4.5 u	4.5 u

(a)
80% = ⁸⁰₁₀₀ = ⁴₅

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

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

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

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

5 u - 15 = 4.5 u + 7
5 u - 4.5 u = 7 + 15
0.5 u = 22 

1 u = 22 ÷ 0.5 = 44

Amount that Oscar has
= 5 u - 15
= 5 x 44 - 15
= 220 - 15
= $205 

(b)
Amount that Nicole has
= 4 u + 15
= 4 x 44 + 15
= 176 + 15
= $191

Answer(s): (a) $205; (b) $191