Number of subsets

Let $a$ and $b$ be the elements of the two sets $A$ and $B,$ respectively. Find the number of ordered pairs $( a, b )$ when $A$ and $B$ satisfy the following two conditions:

$1.$ Both $A$ and $B$ are subsets of the set $\left\{1,3, 5,7,9,11\right\}.$
$2.$ $A - B = \left\{ 1, 3, 5 \right\} .$