Suppose the normal operating time to run a batch is 40 minutes. This run time is roughly to same regardless of the item produced. A setup reduction project has focused on the changeover from making product XA to product XB. The team analyzed the setup steps and identified the external time as 50 minutes and the internal time as 15 minutes. Assuming external steps must be completed before internal steps can be started, what is the minimal setup time? Should the team initially focus its efforts on reducing the time for internal steps or external steps? Explain.