Sabrina had $72 less than Luis. Sabrina spent ¹₃ of her money and Luis spent ²₃ of his money. In the end, Luis and Sabrina had the same amount of money left. Find the amount of money Luis had at first.

	Sabrina	Luis	Difference
Before	3x1 = 3 u	3x2 = 6 u	3 u
Change	- 1x1 = - 1 u	- 2x2 = - 4 u
After	2x1 = 2 u	1x2 = 2 u

Fraction of Sabrina's money left
= 1 - ¹₃
= ²₃

Fraction of Luis's money left
= 1 - ²₃
= ¹₃

Luis and Sabrina had the same amount of money in the end. Make the numerators the same. LCM of 2 and 1 is 2.

²₃ of Sabrina's money = ¹₃ of Luis's money
²₃ of Sabrina's money = ²₆ of Luis's money

Amount that Sabrina had at first = 3 u
Amount that Luis had at first = 6 u

Amount that Sabrina had less than Luis had at first
= 6 u - 3 u
= 3 u

3 u = 72

1 u = 72 ÷ 3 = 24

Amount that Luis had at first
= 6 u
= 6 x 24
= $144

Answer(s): $144