Question 1007722
d^2-9/12d^2 / d^2-d-12/6d
= d^2-9/12d^2 * 6d/d^2-d-12
= (d-3)(d+3)/12d^2 * 6d/(d+3)(d-4)
= (d-3) / 2d(d-4)

Final Answer: (d-3) / 2d(d-4)