There were an equal number of girls in Class J and Class K. ⁵₆ of the students in Class J and ¹₄ of the students in Class K are boys. If there are 98 more boys in Class J than in Class K, what is the total number of students in Class J and Class K?
Fraction of the students in Class J that are girls
= 1 - ⁵₆
=  ¹₆

Fraction of the students in Class K that are girls
= 1 - ¹₄
= ³₄ 

The number of girls in Class J is equal to the number of girls in Class K. LCM of 1 and 3 is 3. Make the numerators the same. 

 1x36x3 Class J = 34 Class K 
 318 Class J = 34 Class K

Number of girls in each class = 3 u

Total number of students in Class J = 18 u
Total number of students in Class K = 4 u

Number of boys in Class J
= 18 u - 3 u
= 15 u

Number of boys in Class K
= 4 u - 3 u
= 1 u

Number of more boys in Class J than Class K
= 15 u - 1 u
= 14 u

14 u = 98

1 u = 98 ÷ 14 = 7

Total number of students
= 18 u + 4 u
= 22 u
= 22 x 7
= 154

Answer(s): 154