2^X - 2^(X-2) = 3(2^13) , what is the value of X

i assume there is a shortcut, or am i supposed to have powers of two memorized that profoundly?

2^X - 2^(X-2) = 3(2^13) , what is the value of X

9

11

13

15

17

i easily eliminated ABC, but was stuck between D and E