Answer:
16 boxes
Explanation:
Since we don't know the amount of boxes he can bring up, will call that x. The elevator has a maximum capacity of 1000 lbs. The delvery person weights 160lbs, which means that the elevator only have 1000 - 160 = 840lbs available for the boxes. Each box weight 50lbs, so we have to multiply that by the amount of boxes, in this case, x boxes, to get the followig equation:
50x = 840
and now we solve for x
x = 840/50
x = 16.8 boxes
since you can't have 0.8 boxes, the maximum amount is 16 boxes.