Please use Johnson's Rule $(>2\frac{M}{C}$ case$)$ to sequence the jobs that require the same operation from M$1-$M$2-$M$3-$M$4-$M$5.$

a$)$ Please find the best job sequence with the lowest completion time.

b$)$ What is the "total idle time" of the best job sequence?

c$)$ What is the "idle time when the machines start" of the best job sequence?

$\backslash$table$[[$Job$,$Processing time $($mins$)],[$M$1,$M$2,$M$3,$M$4,$M$5],[$A$,9,8,7,6,5],[$B$,1,3,5,7,9],[$C$,2,5,6,2,10],[$D$,7,4,4,8,3]]$