Question 40910
6/(2x-12) - 20/(x^2-4x-12)

Factor where you can, as follows:

3/(x-6) 20/[(x-6)(x+2)]

The least common denominators is (x-6)(x+2)
Rewrite eqch fraction with the LCD as its denominator, as follows:

3(x+2)/LCD - 20/LCD

Since both fractions now have the same denominator 
you can subtract, as follows:

[3x+6-20]/LCD
And finally you get the result:
[3x-14]/[(x-6)(x+2)]
Cheers,
Stan H.