Question 243315
{{{15y-60}}}. divide by 15.
15(y-4) ans

{{{9Z^4+27z}}}. divide by 9z.
9z(z^3+3) ans.

{{{-3z^5w^2-18z^3w^4}}}. divide by -3z^3w^2.
-3z^3w^2(z^2-6w^2) ans.

({{{x-5)(x+7)=(x-5)(x+9)}}}. This is an invalid equation.
Cancelling out the (x-5) terms you have:
x+7=x+9 
x-x=9-7
0=2 does not compute.