Answer:
C
Step-by-step explanation:
swap y and x in the function. that is

we get x=4y+5
<em>S</em><em>o</em><em>l</em><em>v</em><em>e </em><em>for </em><em>y</em>
(x-5)/4=y

(f+g)(x)=0
f (x) + g (x)=0
now,
substitute their values
x^2 -4x + x -18 = 0
x^2 -3x -18 =0
x^2 - 6x + 3x - 18 =0
x (x-6) + 3 (x-6) = 0
(x-6)(x+3) = 0
we have to find it's zeroes (or roots) now:
x-6 =0
x = 6
x +3 =0
x = -3
I hope this helps. Since there are verticale angles that’s why I added another x.