Multiple choice general knowledge math & puzzles If a2 – b2 = 18, what is the value of (a + b) if (a – b) = 9 9 2 27 None of the above Reveal answer Fill a bubble to check yourself B Correct answer Explanation Using the identity a²-b² = (a+b)(a-b), we have 18 = (a+b)(9). Therefore a+b = 18/9 = 2. Option B is correct.