In the figure, identify the relationships between \( \angle a \), \( \angle b \), and the other marked angles.<br><br>
Use angle sum of a triangle (\(180^\circ\)), angles on a straight line (\(180^\circ\)), and vertically opposite angles to find \( \angle a \) and \( \angle b \).<br><br>
\( \angle a + \angle b = 140^\circ \).<br><br>
Final Answer: 140&deg;