Answer:
a = 120°
b = 60°
Explanation:
Angle a and 60° are suplementary. The sum of supplementary angles is 180° (straight angle).
a + 60° = 180°
a = 180° - 60°
a = 120°
The sum of angles in the quadrilateral is 360°. Notice how two of the angles in the quadrilateral are marked as right angles (angles marked with a square). Each of them is 90°.
b + 90° + a + 90° = 360°
Substitute a with the value calculated in the previous step.
b + 90° + 120° + 90° = 360°
Solve for b.
b + 300° = 360°
b = 60°