The 2nd competitor ate twice the amount of the 1st competitor's 12 hot dogs So he ate 2*12 = <<2*12=24>>24 hot dogs

The 3rd competitor ate 25% less than the 2nd's 24 hot dogs, which is 24/4 = 6 hot dogs

If the 2nd competitor ate 24 hot dogs, and the 3rd ate 25% less than that, then the 3rd competitor ate 24 - 6 = <<24-6=18>>18 hot dogs

# Answer

18
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
During the hot dog eating contest, the 1st competitor ate 12 hot dogs in 3 minutes.  The 2nd competitor ate twice that amount and the 3rd competitor ate 25% less than the 2nd competitor.  How many hotdogs did the 3rd competitor eat?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
18
During the hot dog eating contest, the 1st competitor ate 12 hot dogs in 3 minutes.  The 2nd competitor ate twice that amount and the 3rd competitor ate 25% less than the 2nd competitor.  How many hotdogs did the 3rd competitor eat?
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