Question 15
If $P=\{p,i,m,s,o\}$ and $C=\{c,i,s,m,o\}$ then $\mathfrak{R}=\{x\mid x\text{ is a subset of }P\}$ and $\mathcal{F}=\{y\mid y\text{ is a subset of }C\}$. Let N be the number of subsets in $\mathfrak{R}$ and M be the number of subsets in $\mathcal{F}$. Let X be the number of common elements of $\mathfrak{R}$ and $\mathcal{F}$. Find $N+M-X$.
Interpretation (editorial): N and M count members of the two displayed families of subsets.
Interpretation (editorial): N and M count members of the two displayed families of subsets.