Answer:
(y+4)
----------------
(y-4)
y cannot equal 4 or 1
Explanation:
y^2 +3y -4
-----------------
y^2 -5y +4
I will factor the numerator and the denominator
(y+4) (y-1)
----------------
(y-4) (y-1)
The factors that must be excluded must be determined before we cancel
y cannot equal 4 or 1 because that would make the denominator go to zero
Cancel y-1 from the numerator and denominator
(y+4)
----------------
(y-4)