1. The problem statement, all variables and given/known data I'm studying for the GMAT and the study materials do not include how to solve this equation. I need to know how to solve it without a calculator. 2. Relevant equations If 2^x - 2^x-2 = 3(2^13), what is the value of X? 3. The attempt at a solution The answer key says the the answer is 15. How did they come to this?