Class 2V and Class 2W have a total of 72 students. ¹₃ of the students in Class 2V and ³₅ of the students in Class 2W are girls. The number of boys in Class 2V is equal to the number of boys in Class 2W. Find the total number of boys in the 2 classes.
Fraction of Class 2V that are boys
= 1 - ¹₃ 
= ²₃

Fraction of Class 2W that are boys
= 1 - ³₅ 
= ²₅ 
 
The number of boys in Class 2V is equal to the number of boys in Class 2W.

The numerators are the same.  

²₃ Class 2V = ²₅ Class 2W 

Number of students in Class 2V = 3 u
Number of students in Class 2W = 5 u

Total number of students 
= 3 u + 5 u
= 8 u

8 u = 72

1 u = 72 ÷ 8 = 9

Number of boys in Class 2V =2 u
Number of boys in Class 2W =2 u

Total number of boys
= 2 u + 2 u
= 4 u
= 4 x 9
= 36

Answer(s): 36