>>542438436
The total degrees on any triangle should add up to 180. The bottom angles are both 80, and if you subtract 20 from one and 30 from the other then you find that the bottom angles of the bottom triangle are 70 and 50. Adding these together gets you 120, meaning that the top angle of the bottom triangle must be 60. Seeing as the lines proceed without any deviation, this means that the bottom angle on the middle triangle must also be 60. Seeing as the left angle of the middle triangle is visibly a right angle (meaning 90), that means that the values of the two known angles add up to 150. 180 - 150 = 30, so the answer is 30.

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