Question 285968
The best way to write this for us is 
   (x-4)/(x^2-3x-4) 
This way clarifies for us exactly what is the numerator and what is the denominator
To make it look nice surround it by 3 { and 3}
{{{(x-4)/(x^2-3x-4)}}}
My guess just looking at it would be that x-4 might be a factor of (x^2-3x-4) 
so we are looking for factors of -4 which add up to -3,
 -4 and 1 work
(x-4)*(x+1)=   (x^2-3x-4) 
   (x-4)/(x^2-3x-4) =
(x-4)/x-4)*(x+1)=
1/x+1