$$

Work is processed in batches at each step. Before a batch is processed at a step, the machine at that step must be set up$.($During a setup, the machine is unable to process any product.$)$ Assume that there is a dedicated setup operator for each machine $($i$.$e$.,$ there is always someone available to perform a setup at each machine$).$ The batch size is the same at each step. So$,$ for example, at Step $1,$ if the batch size is $10$ units, the time to set up and process the entire batch is $190$ minutes. $$This is $110$ minutes for the setup, plus $(8$ minutes per unit $*10$ units$)=190$ minutes. When this step is completed, the batch moves to step $2,$ where the setup occurs at that step, followed by processing at $3$ minutes per unit.