Question

спасайте .... .юю....​

Answer 1

$\frac{n^2-9}{3n-12}:\frac{2n+6}{5n-20}=\frac{(n-3)(n+3)}{3(n-4)}:\frac{2(n+3)}{5(n-4)}=\frac{(n-3)(n+3)}{3(n-4)}*\frac{5(n-4)}{2(n+3)}=\frac{5(n-3)}{6}$