At first, Andy, Vincent and Harry had the same amount of money. After Harry spent some of his money, Andy spent ²₇ of his money and Vincent spent ¹₂ of his money, Andy had $81 more than Vincent. In the end, the total amount of money the three boys had left was $553. How much money did Harry spend?

	Andy	Vincent	Harry	Total
Before	7x2 =  14 u	2x7 = 14 u	14 u
Change	- 2x2 = - 4 u	- 1x7 = - 7 u	- ?
After	5x2 = 10 u	1x7 = 7 u		$553

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

3 u = 81

1 u = 81 ÷ 3 = 27

Amount that Andy and Vincent had in the end
= 10 u + 7 u
= 17 u
= 17 x 27
= $459

Amount that Harry had in the end
= 553 - 459
= $94

Amount that Harry had at first
= 14 u
= 14 x 27
= $378

Amount that Harry spent
= 378 - 94
= $284

Answer(s): $284