Do you know how many floors are in our apartment building all together?
There are 20 floors above ground level and 2 floors below ground level, so we should find the difference of 20 - (-2) = 22. The difference between the highest and lowest floor is 22.
Today I walked -2 x 5 = -10 floors from the 20th floor. My final location after walking down the 10 floors is the floor of my apartment. I live on the 10th floor, so 10 floors below the 20th floor is the 10th floor. My location would be 0.
Yesterday, I walked down 100 feet in 15 minutes. -100/15 = -6.6 feet per minute. Today I walked down 84 feet in 12 minutes. -84/12 = -7 feet per minute. Today I walked down down the stairs faster then yesterday.