At first, Paul, Henry and Zeph had the same amount of money. After Zeph spent some of his money, Paul spent ³₇ of his money and Henry spent ²₃ of his money, Paul had $145 more than Henry. In the end, the total amount of money the three boys had left was $739. How much money did Zeph spend?

	Paul	Henry	Zeph	Total
Before	7x3 =  21 u	3x7 = 21 u	21 u
Change	- 3x3 = - 9 u	- 2x7 = - 14 u	- ?
After	4x3 = 12 u	1x7 = 7 u		$739

The amount that Paul and Henry each had at first is the same.  Make the amount that they each had the same.  LCM of 7 and 3 is 21.

Amount that Paul had more than Henry in the end
= 12 u - 7 u
= 5 u

5 u = 145

1 u = 145 ÷ 5 = 29

Amount that Paul and Henry had in the end
= 12 u + 7 u
= 19 u
= 19 x 29
= $551

Amount that Zeph had in the end
= 739 - 551
= $188

Amount that Zeph had at first
= 21 u
= 21 x 29
= $609

Amount that Zeph spent
= 609 - 188
= $421

Answer(s): $421