Answer:
X = 9
Explanation:
Add like-terms and make it equal to the triangle sum theorem which is 180.
7x+8+7x-1+5x+2=180
19x+9=180
-9 -9
Subtract 9 from 9 and 180, then divide both sides by 19.
19x/19 = x
171/19 = 9
So therefore, x=9.
x = 9
(7x + 8) + (5x +2) + (7x - 1) = 180
19x + 9 = 180
19x = 171
so first option
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