Explanation:
the angles which occupy the same relative position at each intersection where a straight line crosses two others, are called corresponding angles. If the two lines are parallel, the corresponding angles are equal.
two angles, not adjoining one another, that are formed on opposite sides of a line that intersects two other lines, are called alternate angles. If the original two lines are parallel, the alternate angles are equal.
since we are only dealing with parallel lines here, the angles are always equal.
a)
a = 60°, alternate
b)
a = 75°, corresponding
c)
a = 108°, corresponding