Divide 36 into two parts in such a way that $\frac{1}{5}$ of one part is equal to $\frac{1}{7}$ of the other.

Question

$\begin{array}{1 1} (a)\; 16, 20 \\ (b)\; 15,21 \\ (c)\; 14,22\\(d)\; 17, 19 \end{array}$