Answer: a) The size of angle x is
.
b) A. Corresponding angles.
Explanation:
Since AD is parallel to EH and CG is a transversal intersecting them at B and F, then
...(i)
[Pair of corresponding angles are equal lie on the same side of the transversal]
Here,
,

then,
[Substitute values in (i)]
Hence, the size of angle x is
.
Reason for this: Corresponding angles.