`There are 28 rungs in a Ladder`

He was in middle, so let assume it has point x

Then he climbs up 6 rungs, and then 10rungs down.

which is x+6, and then x+6-10=x-4.

then he reaches top by climbing 18rungs, that is x-4+18=x+14.

now, as he was in middle i.e. x and reached top i.e. x+14 means

total # of rungs= 14*2 = 28.