Question 971728
 x^2+3x-28/x^2-36  ;;  This is (x+7) (x-4)/(x+6)(x-6)

 x^2-13x+36/x^2+11x+30 ;;  This is (x-9)(x-4)/(x+6)(x+5)

Numerator
(x+7) (x-4)/(x+6)(x-6)  * (x+6)(x+5)/(x-4)(x-9)

The (x+6) go away and so do the (x-4)

(x+7)/(x-6)  *  (x+5)/(x+9)

You can cancel an (x+6); also, the first term in the numerator is (x+7), not (x-7)