
f(x) + g(x) Substitute/plug in (-5x - 4) into "f(x)" since f(x) = -5x - 4, and plug in (6x - 7) into "g(x)" since g(x) = 6x - 7
(-5x - 4) + (6x - 7) Combine like terms(terms that have the same variable and power/exponent)
-5x + 6x - 4 - 7 (I rearranged the terms to be next to their like term)
x - 11 Your answer is D