$\frac{3a}{25}:\frac{9b}{35}=\frac{3a}{25}\ast <!--\; \ast \; -->\frac{35}{9b}=\frac{a}{5}\ast <!--\; \ast \; -->\frac{7}{3b}=\frac{7a}{15b}$

$\frac{13x}{7y}:\frac{26x}{21y}=\frac{13x}{7y}\ast <!--\; \ast \; -->\frac{21y}{26x}=\frac{1}{1}\ast <!--\; \ast \; -->\frac{3}{2}=1\frac{1}{2}$

$\frac{45ab}{19c}:\frac{27a}{76c}=\frac{45ab}{19c}\ast <!--\; \ast \; -->\frac{76c}{27a}=\frac{5b}{1}\ast <!--\; \ast \; -->\frac{4}{3}=\frac{20b}{3}$