Answer:
The delivery person can bring up max 16 boxes at one time.
Step-by-step explanation:
The elevator can only hold max 850 lbs, and the delivery man weighs 180 lbs.
850-180=670
That means the delivery man can have up to 670 lbs of boxes on the elevator.
670/40=16.75
Which means that the delivery man can hold up to 16 boxes max at one time.