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I don't know the problem, but go on YouTube, type in yourteacher.com / whatever you want to know, and a vid will pop up giving you step by step how to do that kind of problem

Umm. Saying that angle three is a vertical to 1 make perfect sense. Because that means that angle 1 is congruent to angle 3 by ruleof verticalitaztion or something like that. Just go on...