Question

A fraction become 4 when 1 is added to both numerator and denominators it become 7 when 1 is subtracted from both the numerator and denomerator.The numerator of the given fraction is:

Answer 1

Let numerator be x
Denominator be y
So fraction = x/y
Given,
x+1/y+1 = 4
x+1 = 4y+4
x-4y = 3.......... (1)
x-1/y-1 = 7
x-1 = 7y-7
x-7y = - 6.......... (2)
Substracting both these equations
x-4y = 3
x-7y = - 6
- + +
3y = 9
y = 3
Put in eq. (1)
x-4×3 = 3
x = 15
Hence, the numerator of required fraction is 15