There were an equal number of girls in Class M and Class N. ⁵₆ of the pupils in Class M and ¹₆ of the pupils in Class N are boys. If there are 48 more boys in Class M than in Class N, what is the total number of pupils in Class M and Class N?
Fraction of the pupils in Class M that are girls
= 1 - ⁵₆
=  ¹₆

Fraction of the pupils in Class N that are girls
= 1 - ¹₆
= ⁵₆ 

The number of girls in Class M is equal to the number of girls in Class N. LCM of 1 and 5 is 5. Make the numerators the same. 

 1x56x5 Class M = 56 Class N 
 530 Class M = 56 Class N

Number of girls in each class = 5 u

Total number of pupils in Class M = 30 u
Total number of pupils in Class N = 6 u

Number of boys in Class M
= 30 u - 5 u
= 25 u

Number of boys in Class N
= 6 u - 5 u
= 1 u

Number of more boys in Class M than Class N
= 25 u - 1 u
= 24 u

24 u = 48

1 u = 48 ÷ 24 = 2

Total number of pupils
= 30 u + 6 u
= 36 u
= 36 x 2
= 72

Answer(s): 72