I want to find out how many floors are in my apartment building altogether. Since there are 20 floors above ground level and there is 1 floor below ground level. So the difference would be 20-(-1)--21. So the difference between the highest and lowest floor would be 21 floors. In my apartment, I have 21 floors in total.
Today I walked -2x5=-10 floors from the 20 floor. My final location is 6 floors below my apartment. Since I live on the 17th floor, 10 floors below the 20th floor would be 6 floors below me. My location would be -6.
Yesterday I walked down 80 feet in 2 minutes.-80÷2=-40.Today I walked down 75 feet in 10 minutes. -75÷10=-7.5. Yesterday I walked more than today.