Answer:
2x = 84°
Explanation:
the sum of the interior angles of a triangle is 180°
so
180 = 2x + x + 54
180 = 3x + 54
180 - 54 = 3x
126 = 3x
x = 126 : 3
x = 42°
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2x = 42 * 2
2x = 84°
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check
2x + x + 54 = 180
3x + 54 = 180
3 * 42 + 54 = 180
126 + 54 = 180
180 = 180
the answer is good