Question

in a class of 50 students 1/5 are members of drama club 1/10 are member of debating society and the remaining children are in maths or Science club what fraction of the total student are the members of maths and Science club explain?

Answer 1

to find number of students in science and math club we should find number in drama club that is 1/5*50=10.
the number in debating society are 1/10*50=5.the number of students in both of them are 15 and in the math and science are 50-15=35.
in fraction, it is 35/50=7/10.

hope it helps.
#aditya

Answer 2

Let x parts total no. of students are in maths and science club.  
A/Q, 
50/5 + 50/10 + 50/x = 50 
or, 50-15 = 50/x 
or, 35 = 50/x
or, x = 50/35 = 10/7
  or, 1/x = 7/10
 7/10 are members of Maths and Science club.  i.e 50*7/10 = 35 students