\[18 \cdot \left( - \frac{1}{3}\sqrt{5} \right)^{2} - \frac{1}{6} \cdot \left( 4\sqrt{3} \right)^{2} =\]
\[= 18 \cdot \frac{1}{9} \cdot 5 - \frac{1}{6} \cdot 16 \cdot 3 =\]
\[= 10 - 8 = 2\]