Class 1J and Class 1K have a total of 99 students. ¹₄ of the students in Class 1J and ⁴₇ of the students in Class 1K are boys. The number of girls in Class 1J is equal to the number of girls in Class 1K. Find the total number of girls in the 2 classes.
Fraction of Class 1J that are girls
= 1 - ¹₄ 
= ³₄

Fraction of Class 1K that are girls
= 1 - ⁴₇ 
= ³₇ 
 
The number of girls in Class 1J is equal to the number of girls in Class 1K.

The numerators are the same.  

³₄ Class 1J = ³₇ Class 1K 

Number of students in Class 1J = 4 u
Number of students in Class 1K = 7 u

Total number of students 
= 4 u + 7 u
= 11 u

11 u = 99

1 u = 99 ÷ 11 = 9

Number of girls in Class 1J =3 u
Number of girls in Class 1K =3 u

Total number of girls
= 3 u + 3 u
= 6 u
= 6 x 9
= 54

Answer(s): 54