Going down the stairs at home I realize that I forgot my wallet in my room. So from the central step of the stairs I climb again towards my floor. When I had climbed eight steps, I notice that my wallet is in the jacket so again under the stairs to go to work but when I had already gone down twelve steps I realize that what I thought was the wallet is actually a package of tobacco so I climb the 20 steps of the ladder until I reach my floor to take the wallet.
How many steps does the ladder have?
If there is a central step, necessarily the number of steps must be odd so if we take X as the number of steps of the ladder we have that the central step is. Thus, we can obtain the following formula from the statement: from which we deduce that the number of steps is 33.