A fireman stood on the middle rung of a ladder, spraying water onto
a burning building. As the smoke cleared, he stepped up three rungs.
But, waltl A sudden flare-up of flames forced him to climb down
five rungs. He later climbed up seven rungs and worked until the fire was out. At that
point, he climbed up the last six rungs and entered the building. How many rungs were on
the ladder? On which rung did the fireman start on??
