Two-Sided Limits from Graphs

The piecewise function $f(x)$ is plotted above. Think of the pots of gold as open holes and the four leaf clover as a closed hole. Let: $$\begin{align} \color{red}{a}&=\lim_{x\rightarrow 4}f(x)\\ \color{orange}{b}&=f(-1)\\ \color{green}{c}&=\lim_{x\rightarrow 7^+}f(x)\\ \color{blue}{d}&=\lim_{x\rightarrow 7^-}f(x)\\ \end{align}$$