MathNet 2018-part-05 — 181 problems (EN–VI) Question 119

Let $a$ and $b$ be natural numbers such that $2^{a}-2^{b}=240$. What is the value of the expression $a+b$?
(A) 8
(B) 11
(C) 13
(D) 16
(E) None of the above.