Answer:
C
Explanation:
denominator of f(x) can be factored into (x-4)(x+10)
we know that g(x) already has an x+10 in the denominator, so we multiply the numerator and denominator of g(x) with (x+4) so that the function can have a common denominator with f(x) to be added. The function, g(x), then turns into (x-4)/(x-4)(x+10). then, you simply add the numerators (x-16) and (x-4) and leave the denominator alone.