If Opal gives Warren $15, the amount of money she has will be 40% of his. If Warren gives Opal $24, he will have the same amount of money as her. How much money did each of them have?
(a) Warren
(b) Opal

	Case 1		Case 2
	Warren	Opal	Warren	Opal
Before	5 u - 15	2 u + 15	3.5 u + 24	3.5 u - 24
Change	+ 15	- 15	- 24	+ 24
After	5 u	2 u	3.5 u	3.5 u

(a)
40% = ⁴⁰₁₀₀ = ²₅

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

In Case 2, when Warren gives to Opal, there is an internal transfer of money from Warren to Opal. 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 Opal and Warren have
= 5 u + 2 u
= 7 u

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

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

5 u - 15 = 3.5 u + 24
5 u - 3.5 u = 24 + 15
1.5 u = 39 

1 u = 39 ÷ 1.5 = 26

Amount that Warren has
= 5 u - 15
= 5 x 26 - 15
= 130 - 15
= $115 

(b)
Amount that Opal has
= 2 u + 15
= 2 x 26 + 15
= 52 + 15
= $67

Answer(s): (a) $115; (b) $67