Answer:
x = 31
Explanation:
The sum of the internal angles = 180°
then:
2x-5 + x+10 + 2x+20 = 180
5x + 25 = 180
5x = 180 - 25
5x = 155
x = 155/5
Check:
2*31 - 5 + 31+10 + 2*31 + 20 = 180
62-5 + 41 + 62+20 = 180
57 + 41 + 82 = 180
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