At first, Oliver, Japheth and Tommy had the same amount of money. After Tommy spent some of his money, Oliver spent ²₅ of his money and Japheth spent ³₄ of his money, Oliver had $175 more than Japheth. In the end, the total amount of money the three boys had left was $521. How much money did Tommy spend?

	Oliver	Japheth	Tommy	Total
Before	5x4 =  20 u	4x5 = 20 u	20 u
Change	- 2x4 = - 8 u	- 3x5 = - 15 u	- ?
After	3x4 = 12 u	1x5 = 5 u		$521

The amount that Oliver and Japheth 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 Oliver had more than Japheth in the end
= 12 u - 5 u
= 7 u

7 u = 175

1 u = 175 ÷ 7 = 25

Amount that Oliver and Japheth had in the end
= 12 u + 5 u
= 17 u
= 17 x 25
= $425

Amount that Tommy had in the end
= 521 - 425
= $96

Amount that Tommy had at first
= 20 u
= 20 x 25
= $500

Amount that Tommy spent
= 500 - 96
= $404

Answer(s): $404