Part A:
is asking for what the sets B and D have in common:

since B and D only have 4 in common.
Now
is asking for all of the things in the universal set
that are not in
. That's what the little tick mark on the right side means.

Part B:
since those are the things not in B.

is asking for all the things in either
or
.

(We don't need to list 3 twice, even though it was in both sets. )