You can start by setting up an equation. 180=x+4x+x-12. It sould all add up to 180 because angles of a triangle always add up to 180, and x represents the second triangle (you use the second angle as x because the other two angles elaborate off of this second angle). Then you solve. Add 12 to 180 and get 192. Then you can add like terms and make it 192=6x (you add the x's together). Lastly divide 192 by 6 and get 32. So the measurement of angle 2 is 32°. Then you multiply 32 by 4 to get the 1st angle measure, being 128. Lastly subtract 12 from 32 and get 20 for angle three. To check you work add the three angle measures you got and see if they =180, if so then you are correct.
