Answer
$D'$
$2$
Work Step by Step
If the numbers add to 11, they do not add to 4. (So the first part of the event is happening automatically if the second part is happening)
$D$: the numbers do not add to 11
The numbers add to 11: $D'$
$D'=${(5,6)(6,5)}
(The first number is the red die, and the second is the green)
$n(D')=2$
