Class 6N and Class 6P have a total of 42 students. ¹₅ of the students in Class 6N and ⁵₉ of the students in Class 6P are girls. The number of boys in Class 6N is equal to the number of boys in Class 6P. Find the total number of boys in the 2 classes.
Fraction of Class 6N that are boys
= 1 - ¹₅ 
= ⁴₅

Fraction of Class 6P that are boys
= 1 - ⁵₉ 
= ⁴₉ 
 
The number of boys in Class 6N is equal to the number of boys in Class 6P.

The numerators are the same.  

⁴₅ Class 6N = ⁴₉ Class 6P 

Number of students in Class 6N = 5 u
Number of students in Class 6P = 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 6N =4 u
Number of boys in Class 6P =4 u

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

Answer(s): 24