Use Johnson's Rule to Determine the Optimal Sequencing for the Five

Use Johnson's rule to determine the optimal sequencing for the five jobs to be processed on two machines in a fixed order (Machine 1 before Machine 2). The processing times in hours are given in the table below.
a. What is the optimal sequence?
b. What is the total flow time for this sequence?
c. Which job is the first to be scheduled?
Is it scheduled to be the first job or the last?
Explain.
$\begin{array}{|c|c|c|}\hline \text { Job } & \text { Machine 1 } & \text { Machine 2 } \\\hline \text { A } & 10 & 11 \\\hline \text { B } & 8 & 17 \\\hline \text { C } & 14 & 10 \\\hline \mathrm{D} & 13 & 7 \\\hline \mathrm{E} & 10 & 8 \\\hline \mathrm{F} & 25 & 9 \\\hline G & 6 & 15 \\\hline\end{array}$