I was reading this article - http://www.thepokerforum.com/pokermath2.htm

"So that makes the ratio of cards you don't need to need 35 to 12 or around 3 to 1. You would have to put 35/12 into its simplest form and its around 3/1 not exact (the exact figure is 2.916 repeating). Round that off to 3 to 1. The pot would have to be at least 3 times the size of the bet. "

How is that 3-1? What math did he do to figure out it was 3-1?