I wonder how many floors are in my apartment building including above and below ground because there are 20 floors above ground level and four below. So, I would have to do 20 - (-4) = 24. Therefore, there are 24 floors from the highest floor in my apartment building to the lowest.
Today I was on the roof, and I walked down 2 floors per minute. I walked five minutes total and ended up at my apartment. So I walked -2 x 5 = -10 floors, and becasue I ended up at my apartment, I was at a location of 0.
Yesterday, I walked down 100 feet in 15 minutes. -100/15 = -6 2/3 feet per minute. Today, I walked down 84 feet in 12 minutes. 84/12 = -7 feet per minute. Because 7 > 6 2/3, I walked faster today.