Evaluate

$\left[\left(5^{-1} \times 3^{-1}\right)^{-1} \div 6^{-1}\right]=\left[\left(\frac{1}{5} \times \frac{1}{3}\right)^{-1} \div \frac{1}{6}\right]=\left[\left(\frac{1}{15}\right)^{-1} \div \frac{1}{6}\right]=[15 \times 6]=90$