As the sum of the numerator and the denominator of a fraction is 8, we can take the numerator and denominator as x and 8 – x respectively or vice versa.
Here the numerator and the denominator are taken as x and 8 – x respectively.
x/(8-x)
Given that the fraction becomes 3/4 if 3 is added to both the numerator and the denominator each.
(x+3)/(8-x+3)=3/4
(x+3)/(11-x)=3/4
4(x+3)=3(11-x)
4x+12=33-3x
4x+3x=33-12
7x=21
x=3
Hence the value of x is 3. Thus the numerator is 3.
8-x=8-3=5
Hence the denominator is 5.

Thus, the fraction is 3/5