Question 1027185
Fraction skills, factorizing and reducing.


This is not what you mean:
15x^2-9x-6/3x^2-3x-6 *6x^2-6x-12/2x^2+2x-4


The rendering is this:
{{{15x^2-9x-6/3x^2-3x-6 *6x^2-6x-12/2x^2+2x-4}}}


Best guess is you really have this:
{{{((15x^2-9x-6)/(3x^2-3x-6)) *((6x^2-6x-12)/(2x^2+2x-4))}}}


{{{((3(5x^2-3x-2))/(3(x^2-x-2)))((2*3(x^2-x-2))/(2(x^2+x-2)))}}}


See some common factors in numerator and denominator, and cancel them as redundant factors of 1.
{{{(((5x^2-3x-2))/((x^2-x-2)))((3(x^2-x-2))/((x^2+x-2)))}}}
and
{{{(((5x^2-3x-2))/(1))((3)/((x^2+x-2)))}}}


{{{(3(5x^2-3x-2))/(x^2+x-2)}}}


Finish the multiplication to simplify,
{{{(15x^2-9x-6)/(x^2+x-2)}}}