Answer
59°
Explanation
There are 2 parallel line and one transverse.
Angles in a straight line add up to 180°
∴ 180 - (2a + 3) = 180 - 2a -3
= 177 - 2a
The angle (177 - 2a) corresponds to angle a in the diagram. The two corresponding angles are equal.
∴ 177 - 2a = a
177 = a + 2a
3a = 177
a = 177/3
= 59°
