Given that f(x)=x2+8x\displaystyle {f{{\left({x}\right)}}}={x}^{{2}}+{8}{x} and g(x)=4x+8\displaystyle {g{{\left({x}\right)}}}=-{4}{x}+{8}, find
(a) (f+g)(4)\displaystyle {\left({f}+{g}\right)}{\left({4}\right)}=  
(b) (fg)(4)\displaystyle {\left({f}-{g}\right)}{\left({4}\right)}=  
(c) (fg)(4)\displaystyle {\left({f}{g}\right)}{\left({4}\right)}=  
(d) (fg)(4)\displaystyle {\left(\frac{{f}}{{g}}\right)}{\left({4}\right)}=