Question 97069

x is the middle rung, so add all times he climbs above this rung

x + 3 + 2(since he dropped 5, only count the 2 above) + 6

So there are 11 steps above the middle rung, therefore there must be 11 steps BELOW the middle rung.  Add the middle rung and you have 
11 + 11 + 1 = 23 rungs on the ladder