To simplify the expression stated, it is better to write it in the numerical form. The statement is:
quantity 12 x plus 36 over quantity x squared minus 4 x minus 21
The numerical form is:
12x+36 / (x²-4x-21)
Simplifying,
12x+36 / (x²-4x-21)
12 (x+3) / (x+3)(x-7)
We can cancel the x+3 term, leaving only:
12/(x-7)
