Subsets...!?!

THE solution is too simple see The subsets of $\boxed{B}$ are 15 more than that in $\boxed{C}$ The number of subsets of a set is given by the formula - $2^n$ where $\boxed{n}$ is the number of elements in a set So $2^n$ must always be even , even after subtraction from any power of 2 But here it is positive which clearly states that $\boxed{C}$ has only 1 subset so the set $\boxed{C}$ is a null set you can compare $2^x$ - $2^0$ = 15 and solve for the value of $\boxed{x}$ which would come out to be 4 since set $\boxed{A}$ has twice the elements of set $\boxed{B}$ therefore you can apply the similar formula of $2^n$ to the set $\boxed{A}$ and subtract it from the subsets in $\boxed{B}$ AND ANSWER WILL BE $\boxed{240}$