Class 5R and Class 5S have a total of 42 students. ¹₆ of the students in Class 5R and ³₈ of the students in Class 5S are girls. The number of boys in Class 5R is equal to the number of boys in Class 5S. Find the total number of boys in the 2 classes.
Fraction of Class 5R that are boys
= 1 - ¹₆ 
= ⁵₆

Fraction of Class 5S that are boys
= 1 - ³₈ 
= ⁵₈ 
 
The number of boys in Class 5R is equal to the number of boys in Class 5S.

The numerators are the same.  

⁵₆ Class 5R = ⁵₈ Class 5S 

Number of students in Class 5R = 6 u
Number of students in Class 5S = 8 u

Total number of students 
= 6 u + 8 u
= 14 u

14 u = 42

1 u = 42 ÷ 14 = 3

Number of boys in Class 5R =5 u
Number of boys in Class 5S =5 u

Total number of boys
= 5 u + 5 u
= 10 u
= 10 x 3
= 30

Answer(s): 30