..
x^2 +3x - 28 factors as ( x +7) ( x - 4)
x^2 - 7x - 12 factors as ( x - 3) ( x - 4)
So....the (x - 4) factors will "cancel" in the numerator /denomnator and we are left with
[ x + 7 ]
_______
[ x - 3 ]
