$\frac{9x^{3}}{5xy} \div \frac{18x}{10y^{2}} = $

$\frac{x^{2}+4x-5}{x-1} \div \frac{x+5}{x-3} = $

$\frac{x+4}{x^{3}} \times \frac{x^{5}}{x^{2}+7x+12} = $

$\frac{x^{2}+2x-35}{x^{2}+4x-21} \times \frac{x+9}{x^{2}+18x+81} = $

$\frac{4-t^{2}}{t+2} \div \frac{t-2}{t^{2}+4t+4} = $