Given the Earliest and Latest Finish Times for Each of These

Essay

Given the earliest and latest finish times for each of these activities, what are the activity lengths?
$$\begin{array} { | c | c | c | c | } \hline \text { Activity } & \text { EF } & \text { LF } & \text { Predecessors } \\\hline \text { A } & 3 & 3 & \cdots \\\hline \text { B } & 10 & 10 & \text { A } \\\hline \text { C } & 5 & 13 & \text { A } \\\hline \text { D } & 18 & 18 & \text { B } \\\hline \text { E } & 15 & 18 & \text { B } \\\hline \text { F } & 11 & 19 & \text { C } \\\hline \text { G } & 8 & 19 & \text { C } \\\hline \text { H } & 23 & 23 & \text { D, E } \\\hline \text { I } & 15 & 23 & \text { F, G } \\\hline \text { J } & 24 & 24 & \text { H, I } \\\hline\end{array}$$