Determine the order of the coset containing each of the following elements in the respective quotient groups. ($U(n)$ is the multiplicative group of units in $\mathbb{Z}_n$.)

element	quotient group	order
$( 2, 1 )$	$\mathbb{Z}_{18}\times\mathbb{Z}_{18}/ \langle ( 10, 5 ) \rangle$
$( 10, 1 )$	$\mathbb{Z}_{20}\times\mathbb{Z}_{8}/ \langle ( 5, 3 ) \rangle$
$( 18, 11 )$	$\mathbb{Z}_{21}\times U(18)/\langle ( 6, 5 ) \rangle$
$( 9, 11 )$	$\mathbb{Z}_{12}\times U(18)/\langle ( 6, 13 ) \rangle$