Let
\(f(x) = \left\{ \begin{array}{cl} ax+3, &\text{ if }x>2, \\ x-5 &\text{ if } -2 \le x \le 2, \\ 2x-b &\text{ if } x <-2. \end{array} \right.\)
Find a+b if the piecewise function is continuous (which means that its graph can be drawn without lifting your pencil from the paper).