If Lynn gives Eric $18, the amount of money she has will be 75% of his. If Eric gives Lynn $6, he will have the same amount of money as her. How much money did each of them have?
(a) Eric
(b) Lynn

	Case 1		Case 2
	Eric	Lynn	Eric	Lynn
Before	4 u - 18	3 u + 18	3.5 u + 6	3.5 u - 6
Change	+ 18	- 18	- 6	+ 6
After	4 u	3 u	3.5 u	3.5 u

(a)
75% = ⁷⁵₁₀₀ = ³₄

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

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

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

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

4 u - 18 = 3.5 u + 6
4 u - 3.5 u = 6 + 18
0.5 u = 24 

1 u = 24 ÷ 0.5 = 48

Amount that Eric has
= 4 u - 18
= 4 x 48 - 18
= 192 - 18
= $174 

(b)
Amount that Lynn has
= 3 u + 18
= 3 x 48 + 18
= 144 + 18
= $162

Answer(s): (a) $174; (b) $162