Answer:
17.83 boxes
Explanation:
Lets represent the number of boxes of books that can be brought up per time = x
From the question: The delivery person weighs 170lb and each box of books weighs 60 lb. The maximum capacity of the elevator is 1240lb.
Hence we have the Algebraic Expressions
170lb + 60 × x = 1240lb
170lb + 60x = 1240lb
Collect like terms
60x = 1240lb - 170lb
60x = 1070lb
x = 1070lb/60
x = 17.833333333
x = 17.83 boxes
Therefore, the delivery person can bring up 17.83 boxes per time