Class 4K and Class 4L have a total of 45 students. ¹₆ of the students in Class 4K and ⁴₉ of the students in Class 4L are girls. The number of boys in Class 4K is equal to the number of boys in Class 4L. Find the total number of boys in the 2 classes.
Fraction of Class 4K that are boys
= 1 - ¹₆ 
= ⁵₆

Fraction of Class 4L that are boys
= 1 - ⁴₉ 
= ⁵₉ 
 
The number of boys in Class 4K is equal to the number of boys in Class 4L.

The numerators are the same.  

⁵₆ Class 4K = ⁵₉ Class 4L 

Number of students in Class 4K = 6 u
Number of students in Class 4L = 9 u

Total number of students 
= 6 u + 9 u
= 15 u

15 u = 45

1 u = 45 ÷ 15 = 3

Number of boys in Class 4K =5 u
Number of boys in Class 4L =5 u

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

Answer(s): 30