Given f(x)=x2+10x\displaystyle {f{{\left({x}\right)}}}={x}^{{2}}+{10}{x}, find the average rate of change of f(x)\displaystyle {f{{\left({x}\right)}}} on the interval [3,3+h]\displaystyle {\left[-{3},-{3}+{h}\right]}. Your answer will be an expression involving h\displaystyle {h}.