Jan is not correct. The opposite of any number will not always be a positive. This is because the opposite of a positive number is negative and the opposite of a negative number is positive.
Basically, opposite numbers are numbers that are the same distance to 0 on a number line. If we were to have a positive 1, the opposite of that number would be a -1, because that's equally distant from 0 on a number line.
The most likely measurement for a two-story building would be 20 feet. 6 inches, 25 inches, and 6 feet all are way too short for a two-story building.
