He then climbed up 6 rungs before the heat of the flames caused him to come down 10 rungs. After some minutes he was able to climb 18 rungs to the very top of the ladder. How many rungs did the ladder have?
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29 rungs
The firefighter is standing on the middle rung. He goes up 6 rungs so he is now at M+6, he now goes down 10 rungs so he is now at M-4 he goes up 18 rungs so he is now at M+14=T. 14 rungs from the top, 14 rungs from the bottom and the middle rung. 14+14+1=29!
The firefighter is standing on the middle rung. He goes up 6 rungs so he is now at M+6, he now goes down 10 rungs so he is now at M-4 he goes up 18 rungs so he is now at M+14=T. 14 rungs from the top, 14 rungs from the bottom and the middle rung. 14+14+1=29!
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29 rungs. he started in the middle, went up 6, then down 10 which cancels the 6 up, and is the sames as going 4 down from the middle. then went up 18 to the top, he was down 4 from the middle, so subtract 4 from 18, you have up from the middle to reach the top and 14 to the bottom. thats 28, plus the middle rung he started on. 29
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36