Find the common factors of:

$16$ and $20$

Find the common factors of:

$21$ and $35$

Find the common factors of:

$3, 6$ and $9$

Find the common factors of:

$8, 12$ and $20$

Find the common factors of:

$45, 60$ and $105$

Find the first three common multiples of:

$8$ and $12$

Find the first three common multiples of:

$6$ and $9$

Find the first three common multiples of:

$10$ and $25$