Class 6K and Class 6L have a total of 135 students. ¹₆ of the students in Class 6K and ⁴₉ of the students in Class 6L are boys. The number of girls in Class 6K is equal to the number of girls in Class 6L. Find the total number of girls in the 2 classes.
Fraction of Class 6K that are girls
= 1 - ¹₆ 
= ⁵₆

Fraction of Class 6L that are girls
= 1 - ⁴₉ 
= ⁵₉ 
 
The number of girls in Class 6K is equal to the number of girls in Class 6L.

The numerators are the same.  

⁵₆ Class 6K = ⁵₉ Class 6L 

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

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

15 u = 135

1 u = 135 ÷ 15 = 9

Number of girls in Class 6K =5 u
Number of girls in Class 6L =5 u

Total number of girls
= 5 u + 5 u
= 10 u
= 10 x 9
= 90

Answer(s): 90