Station A has $3$ parallel operators, A$1,$ A$2,$ and A$3.$ Station C has $2$ parallel operators, C$1$ and C$2.$ Each unit only needs to be processed by one of the operators A$1,$ A$2$ and A$3.$ After being processed at Station B$,$ a unit then needs to be processed by either C$1$ or C$2.$ The process time of the individual operators are given as follows.

roduction process is shown in the figure above. The drilling operation occurs separately from, and simultaneously with the sawing and sanding operations. Welding starts when both drilling and sanding operations have been completed. After welding, a product needs to go through only one of the three assembly operations $($the operations are in parallel, where parallel lines perform the exact same operation$).$ Considering the process times at stations, what is the process time of the system $($in min$/$unit$)?$