Dodatnia liczba x stanowi 70% liczby y. Wówczas

$\displaystyle y= \frac{13}{10}x$\displaystyle y= \frac{13}{10}x

$\displaystyle y= \frac{7}{10}x$\displaystyle y= \frac{7}{10}x

$\displaystyle y= \frac{10}{7}x$\displaystyle y= \frac{10}{7}x

$\displaystyle y= \frac{10}{13}x$\displaystyle y= \frac{10}{13}x