The distance formula for two points on a number is | a-b |, that is the absolute value of a - b. In this case a = 137.5 and b = -62.5, with these numbers in mind we can make substitute for a and b and solve, | 137.5 - -62.5 | = n. Since when there are two negative signs present they turn positive, we can see that the distance between point a and point b and therefore the distance between the two elevators in 200 feet.
| 137.5 - -62.5 | = n
| 137.5 + 62.5 | = 200
