Answer
a) $\emptyset,\{a\},\{b\},\{a,b\}$
$\phantom{a)} \emptyset,\{a\},\{b\},\{c\},\{a,b\},\{a,c\},\{b,c\},\{a,b,c\}$
b) yes
Work Step by Step
a) The subsets of $P=\{a,b\}$ are
$$
\emptyset,\{a\},\{b\},\{a,b\}
.$$
The subsets of $S=\{a,b,c\}$ are
$$
\emptyset,\{a\},\{b\},\{c\},\{a,b\},\{a,c\},\{b,c\},\{a,b,c\}
.$$
b) Yes, $A$ is a subset of $B$ since all elements of $A$ are elements of $B$.
