Answer:
21 box of books can be brought up by the delivery person at one time
Step-by-step explanation:
Here, we want to know the number of box of books that the delivery person could bring up at one time.
Let the number of boxes be x , so the total mass of the boxes that could come up at a time will be x * 40 = 40x lb
Let’s add this to the mass of the delivery person = 150 lb
So the total mass going inside the lift would be 150 + 40x
So we have to equate this to the maximum capacity of the lift;
150 + 40x = 1020
40x = 1020 - 150
40x = 870
x = 870/40
x = 21.75
Now since we cannot have fractional boxes, the number of boxes that could come into the lift without exceeding the maximum capacity of the lift is 21