Question 181244
x^2-x-6  over    x^2-2x-8   Divided by  x^2-9 over x^2+7x+12


solution:
Numerator =  x^2-x-6  / x^2-2x-8
           =x^2-x-6  /(x-4)(x+2)
             =x-3)(x+2)/(x-4)(x+2)=x-3/x+4
denominator = (x-3)(x+3)/(x+4)(x+3)=  (x-3)/x+4
nm/dn =  1
(QED)