At first, Zane, Tommy and Riordan had the same amount of money. After Riordan spent some of his money, Zane spent ²₇ of his money and Tommy spent ¹₂ of his money, Zane had $84 more than Tommy. In the end, the total amount of money the three boys had left was $594. How much money did Riordan spend?

	Zane	Tommy	Riordan	Total
Before	7x2 =  14 u	2x7 = 14 u	14 u
Change	- 2x2 = - 4 u	- 1x7 = - 7 u	- ?
After	5x2 = 10 u	1x7 = 7 u		$594

The amount that Zane and Tommy each had at first is the same.  Make the amount that they each had the same.  LCM of 7 and 2 is 14.

Amount that Zane had more than Tommy in the end
= 10 u - 7 u
= 3 u

3 u = 84

1 u = 84 ÷ 3 = 28

Amount that Zane and Tommy had in the end
= 10 u + 7 u
= 17 u
= 17 x 28
= $476

Amount that Riordan had in the end
= 594 - 476
= $118

Amount that Riordan had at first
= 14 u
= 14 x 28
= $392

Amount that Riordan spent
= 392 - 118
= $274

Answer(s): $274