Given that $\displaystyle f(x)=\frac{4}{x-9}$ and $\displaystyle g(x)=\frac{3}{x + 4}$, find the following

(a) $(f+g)(x)$= help (formulas)
and its domain is help (intervals)

(b) $(f-g)(x)$= help (formulas)
and its domain is help (intervals)

(c) $(fg)(x)$= help (formulas)
and its domain is help (intervals)

(d) $(f/g)(x)$= help (formulas)
and its domain is help (intervals)