For the functions $f(x)=6-x^2$ and $g(x)=x^2+2x-80$, find $f+g$, $f-g$, $fg$, and $\frac{f}{g}$. Determine the domain for each function.
$(f+g)(x)=2x-74$ (Simplify your answer.)
What is the domain of $f+g$? Select the correct choice below and, if necessary, fill in the answer box to complete your choice.
A. The domain of $f+g$ is {}.
(Use a comma to separate answers as needed.)
B. The domain of $f+g$ is $(-\infty, \infty)$.
(Type your answer in interval notation.)
C. The domain of $f+g$ is $\emptyset$.
$(f-g)(x)=$ (Simplify your answer.)