Answer:
170
Step-by-step explanation:
Assuming no safety stock is used, the reorder point (ROP) can be given by:
ROP = lead time x average daily demand.
The lead time is 5 days.
Average daily demand (ADD) is given by:

Therefore, the reorder point is:

This means that Duncan's Stationery Shop should not let inventory fall under 170 binders in order to meet their average daily demand.