Answer:
9/16
Explanation:
Let the original fraction be
x/y 
Then 
x+3/y=3/4 
and 
x/y-7=1 
Look at 2nd fraction, rearrange it such that you multiply by "y-7" on both sides 
x=y-7 
Substitute this into 1st fraction: 
x-7+3/y=3/4 
Now we can solve this for y: cross-multiply --> (Note: y-7+3 = y-4) 
4(y-4)=3y 
y=16 
Sub this back into "x = y-7" to get x 
x=16-7=9 
Therefore the original fraction is: 
9/16