Answer:
(c) 285°
Explanation:
remember, the interception angles of parallel lines with an intercepting line are the same for each parallel line (logically, otherwise they would not be parallel).
and the angles on top of an intercepted line are the same as at the bottom, they are just left-right mirrored.
so, the inner angle of the 45° intercepting line with the dotted line (also parallel to the other 2 lines, I assume) is also 45°.
and the inner angle of the 30° intercepting line with the dotted line is also 30°.
x is now simply the sum of the supplementary angles of these 2 angles.
supplementary means 2 angles together have 180°, which is always the sum of all angles around a single point on one side of a line (as the line is like the diameter of a circle and the point is the center of that imaginary circle, and a half-circle has always 180°).
the supplementary angle of 45° is
45 + s = 180
s = 180 - 45 = 135°
the supplementary angle of 30° is
30 + s = 180
s = 180 - 30 = 150°
x = 135 + 150 = 285°