If product of two number is $25 \large\frac{3}{8}$ if one of them is $15 \large\frac{9}{40}$, then other number is

Question

$\begin{array}{1 1} \large\frac{2}{3} \\1 \large\frac{2}{3} \\5\large\frac{2}{3} \\\large\frac{9}{7} \end{array}$