At first, John, Simon and Billy had the same amount of money. After Billy spent some of his money, John spent ²₇ of his money and Simon spent ²₃ of his money, John had $88 more than Simon. In the end, the total amount of money the three boys had left was $335. How much money did Billy spend?

	John	Simon	Billy	Total
Before	7x3 =  21 u	3x7 = 21 u	21 u
Change	- 2x3 = - 6 u	- 2x7 = - 14 u	- ?
After	5x3 = 15 u	1x7 = 7 u		$335

The amount that John and Simon 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 John had more than Simon in the end
= 15 u - 7 u
= 8 u

8 u = 88

1 u = 88 ÷ 8 = 11

Amount that John and Simon had in the end
= 15 u + 7 u
= 22 u
= 22 x 11
= $242

Amount that Billy had in the end
= 335 - 242
= $93

Amount that Billy had at first
= 21 u
= 21 x 11
= $231

Amount that Billy spent
= 231 - 93
= $138

Answer(s): $138