At first, Seth, Cody and Andy had the same amount of money. After Andy spent some of his money, Seth spent ²₇ of his money and Cody spent ³₅ of his money, Seth had $330 more than Cody. In the end, the total amount of money the three boys had left was $1330. How much money did Andy spend?

	Seth	Cody	Andy	Total
Before	7x5 =  35 u	5x7 = 35 u	35 u
Change	- 2x5 = - 10 u	- 3x7 = - 21 u	- ?
After	5x5 = 25 u	2x7 = 14 u		$1330

The amount that Seth and Cody each had at first is the same.  Make the amount that they each had the same.  LCM of 7 and 5 is 35.

Amount that Seth had more than Cody in the end
= 25 u - 14 u
= 11 u

11 u = 330

1 u = 330 ÷ 11 = 30

Amount that Seth and Cody had in the end
= 25 u + 14 u
= 39 u
= 39 x 30
= $1170

Amount that Andy had in the end
= 1330 - 1170
= $160

Amount that Andy had at first
= 35 u
= 35 x 30
= $1050

Amount that Andy spent
= 1050 - 160
= $890

Answer(s): $890