Answer:
x = 28
Explanation:
Given that lines AB and CD are straight lines that intersects at O, it follows that the pair of opposite vertical angles formed are congruent.
Thus,
<AOD = <BOC
<AOD = 152°
<BOC = 3x + x + (x + 12) (angle addition postulate)
<BOC = 5x + 12
Since <AOD = <BOC, therefore,
152° = 5x + 12 (substitution)
152 - 12 = 5x (subtraction property of equality)
140 = 5x
140/5 = x (division property of equality)
28 = x
x = 28