The sum of functions is given as:

In this case we have:
![(f+g)(x)=5x+\sqrt[]{x-1}](https://tex.z-dn.net/?f=%28f%2Bg%29%28x%29%3D5x%2B%5Csqrt%5B%5D%7Bx-1%7D)
The domain of the functions is any number that makes the squared root a real number, then:

Hence the domain of the functions is:
Cos(x°) = (√3)/2
cos⁻¹[(√3)/2] = x°, that means x° = 30°
The answer is C.
It has a negative slope (-40) and a y-intercept at 200.