A Network Consists of the Following List A Draw the Network Diagram

A network consists of the following list. Times are given in weeks.
$$\begin{array} { | c | c | c | } \hline \text { Activity } & \text { Preceding } & \text { Duration } \\\hline \text { A } & - - & 9 \\\hline \text { B } & \mathrm { A } & 2 \\\hline \text { C } & \mathrm { A } & 12 \\\hline \text { D } & \mathrm { A } & 5 \\\hline \text { E } & \mathrm { B } & 6 \\\hline \text { F } & \mathrm { B } & 8 \\\hline \text { G } & \mathrm { C } , \mathrm { F } & 3 \\\hline \text { H } & \mathrm { D } & 2 \\\hline \text { I } & \mathrm { H } & 8 \\\hline \text { J } & \text { G, I } & 6 \\\hline \text { K } & \text { E, J } & 2 \\\hline\end{array}$$ a. Draw the network diagram.
b. Which activities form the critical path?
c. How much slack exists at activities A and F?
d. What is the duration of the critical path?