a) $$14 \times \frac{\pi}{6} - 2 \times \frac{\pi}{3} = \frac{7\pi}{3} - \frac{2\pi}{3} = \frac{5\pi}{3}$$
б) $$\frac{2\pi}{3} + (-\frac{\pi}{3}) = \frac{\pi}{3}$$