Find the amount of subgroups of order $3$ and $21$ in non-cyclic abelian group of order $63$

Find the amount of subgroups of order $ 3$ and $ 21$ in non-cyclic abelian group of order $ 63$ .

In first case I found the amount of elements that have order $ 3$ – there are $ 8$ of them, in second case there are $ 48$ elements of order $ 21$ . How do I connect these values with the amount of subgroups now?