Answer:
24
Explanation:
Since the lines L and M are parallel:
Angle 1 and and 2 are alternate and their measurement is equal.
3x + 6 = 6x - 12 (we multiplied 6 with inside the parenthesis)
6 + 12 = 6x - 3x
18 = 3x divide both sides by 3
6 = x to find the angle measure replace x with 6
3x + 6 is 3*6 + 6 = 24