At the musical performance, there were 36 less boys than girls. After ²₅ of the boys and ²₃ of the girls had left the hall, there was an equal number of boys and girls that remained behind. Find the number of boys who were present at the musical performance at first.

	Boys	Girls	Less
Before	5x1 = 5 u	3x3 = 9 u	4 u
Change	- 2x1 = - 2 u	- 2x3 = - 6 u
After	3x1 = 3 u	1x3 = 3 u

Fraction of boys that remained
= 1 - ²₅
= ³₅

Fraction of girls that remained
= 1 - ²₃
= ¹₃

The number of boys and girls in the end is the same. Make the number of boys and girls in the end the same. LCM  of 3 and 1 is 3.

^3x1_5x1 Boys = ^1x3_3x3 Girls
³₅ Boys = ³₉ Girls

Total boys at first = 5 u
Total girls at first = 9 u

Number of less boys than girls at first
= 9 u - 5 u
= 4 u

4 u = 36

1 u = 36 ÷ 4 = 9

Number of boys at first
= 5 u
= 5 x 9
= 45

Answer(s): 45