Which rational expression is equivalent to 1 / (x+4) + 3 / (x-5)

(4x+7) / (x^2-x-20)

Step-by-step explanation:

To simplify them into one, you need to make the common denominator (x+4) (x-5).

[1 (x-5) + 3 (x+4) ] / (x-5) (x+4)

(x-5+3x+12) / (x-5) (x+4)

(4x+7) / (x-5) (x+4)

I'm not sure how simplified you want it, but as I put at the top, the (x-5) (x+4) can be simplified to x^2-x-20