[tex] \frac{5x}{2y}= 1,25 \\ \\ \frac{5x}{2y}= \frac{5}{4} \\ \\ \frac{5}{2}*\frac{x}{y}= \frac{5}{4} \\ \\ \frac{x}{y}= \frac{5}{4}: \frac{5}{2} \\ \\ \frac{x}{y}= \frac{5}{4}* \frac{2}{5} \\ \\ \frac{x}{y}= \frac{1}{2} \\ \\ \frac{y}{x}= \frac{2}{1} = \boxed{2}[/tex]