At first, Xavier, Pierre and David had the same amount of money. After David spent some of his money, Xavier spent ³₅ of his money and Pierre spent ³₄ of his money, Xavier had $81 more than Pierre. In the end, the total amount of money the three boys had left was $484. How much money did David spend?

	Xavier	Pierre	David	Total
Before	5x4 =  20 u	4x5 = 20 u	20 u
Change	- 3x4 = - 12 u	- 3x5 = - 15 u	- ?
After	2x4 = 8 u	1x5 = 5 u		$484

The amount that Xavier and Pierre each had at first is the same.  Make the amount that they each had the same.  LCM of 5 and 4 is 20.

Amount that Xavier had more than Pierre in the end
= 8 u - 5 u
= 3 u

3 u = 81

1 u = 81 ÷ 3 = 27

Amount that Xavier and Pierre had in the end
= 8 u + 5 u
= 13 u
= 13 x 27
= $351

Amount that David had in the end
= 484 - 351
= $133

Amount that David had at first
= 20 u
= 20 x 27
= $540

Amount that David spent
= 540 - 133
= $407

Answer(s): $407