Class 2N and Class 2P have a total of 42 students. ¹₅ of the students in Class 2N and ⁵₉ of the students in Class 2P are girls. The number of boys in Class 2N is equal to the number of boys in Class 2P. Find the total number of boys in the 2 classes.
Fraction of Class 2N that are boys
= 1 - ¹₅ 
= ⁴₅

Fraction of Class 2P that are boys
= 1 - ⁵₉ 
= ⁴₉ 
 
The number of boys in Class 2N is equal to the number of boys in Class 2P.

The numerators are the same.  

⁴₅ Class 2N = ⁴₉ Class 2P 

Number of students in Class 2N = 5 u
Number of students in Class 2P = 9 u

Total number of students 
= 5 u + 9 u
= 14 u

14 u = 42

1 u = 42 ÷ 14 = 3

Number of boys in Class 2N =4 u
Number of boys in Class 2P =4 u

Total number of boys
= 4 u + 4 u
= 8 u
= 8 x 3
= 24

Answer(s): 24