5tg(7π/12 + 3а)-5tg( π/3 + 3a) / 1+tg(7π/12 + 3a) tg( π/3 + 3a)

Решите задачу:

$\frac{5tg(\frac{7\pi }{12}+3a)-5tg(\frac{\pi}{3}+3a)}{1+tg(\frac{7\pi}{12}+3a)\cdot tg(\frac{\pi}{3}+3a)} =5\cdot tg( \frac{7\pi }{12}+3a-\frac{\pi}{3}-3a)=5\cdot tg\frac{3\pi}{12}= \\\\=5\cdot tg\frac{\pi}{4}=5\cdot 1=5\\\\\\Formyla:\; \; tg( \alpha- \beta )=\frac{tg \alpha -tg \beta }{1+tg \alpha \cdot tg \beta \beta }$