$\frac{144°}{180°} = \frac{x}{\pi} \; \text{so} \; \frac{4}{5}\pi = x$

$\frac{3}{2} \pi + \frac{1}{6}\pi = \frac{10}{6}\pi = \frac{5}{3}\pi$

$\frac{5 \cdot 180°}{9} = 5 \cdot 20°= 100°$