If Tina gives Jack $16, the amount of money she has will be 75% of his. If Jack gives Tina $5, he will have the same amount of money as her. How much money did each of them have?
(a) Jack
(b) Tina

	Case 1		Case 2
	Jack	Tina	Jack	Tina
Before	4 u - 16	3 u + 16	3.5 u + 5	3.5 u - 5
Change	+ 16	- 16	- 5	+ 5
After	4 u	3 u	3.5 u	3.5 u

(a)
75% = ⁷⁵₁₀₀ = ³₄

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

In Case 2, when Jack gives to Tina, there is an internal transfer of money from Jack to Tina. 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 Tina and Jack have
= 4 u + 3 u
= 7 u

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

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

4 u - 16 = 3.5 u + 5
4 u - 3.5 u = 5 + 16
0.5 u = 21 

1 u = 21 ÷ 0.5 = 42

Amount that Jack has
= 4 u - 16
= 4 x 42 - 16
= 168 - 16
= $152 

(b)
Amount that Tina has
= 3 u + 16
= 3 x 42 + 16
= 126 + 16
= $142

Answer(s): (a) $152; (b) $142