At first, Liam, Ian and Perry had the same amount of money. After Perry spent some of his money, Liam spent ²₇ of his money and Ian spent ¹₂ of his money, Liam had $36 more than Ian. In the end, the total amount of money the three boys had left was $380. How much money did Perry spend?

	Liam	Ian	Perry	Total
Before	7x2 =  14 u	2x7 = 14 u	14 u
Change	- 2x2 = - 4 u	- 1x7 = - 7 u	- ?
After	5x2 = 10 u	1x7 = 7 u		$380

The amount that Liam and Ian 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 Liam had more than Ian in the end
= 10 u - 7 u
= 3 u

3 u = 36

1 u = 36 ÷ 3 = 12

Amount that Liam and Ian had in the end
= 10 u + 7 u
= 17 u
= 17 x 12
= $204

Amount that Perry had in the end
= 380 - 204
= $176

Amount that Perry had at first
= 14 u
= 14 x 12
= $168

Amount that Perry spent
= 168 - 176
= $-8

Answer(s): $-8