when the hotel manager rides down 2 floors from 19 floor, it means he stops at floor 17, the floor he rides down as negative integer = -2
then he rides down 3 floors and it means he stops at floor 14, so the number of floors he rides down from there = -3
then he rides to the first floor as there is no number 13 floor it means he rides down 12 floor = -12
the addition expression using negative integers to show the number of total floors the hotel manager rode down the elevator = -2 + (-3) + (-12) = -17