Since there are 20 floors all together in my apartment building. 20 floors above ground and 2 floors underground which is the basement and boiler room. I will have to do is find the difference 20-(-2)= 22. The highest and lowest floor in the building is 22 floors.
I walked -2x 7= -14 from the 20th floor. My final location is -4 from my apartment because I live on the 10th floor and 10 floors below the 20th would be -4 below me. So, my location is -4.
Yesterday I walked down 58 feet in 10 minutes. -58/10 = -5.8 feet per minute. Today I walked 90 feet in 15 minutes. -90/15 = -6 feet per minute. So, I walked faster today then I did yesterday.