Convert the logarithmic equation into exponential form. The statement log_2(x + 5) = 4 means x + 5 = 2^4. Now calculate 2^4 = 16, so x + 5 = 16. Subtract 5 from both sides: x = 16 - 5 = 11. Finally, check the domain: x + 5 must be positive, and 11 + 5 = 16 > 0, so the answer is valid.