INFORMATION:LettersPQSymbols+ - 11 P 3 Q 2 = 12 → 11 + 3 - 2 = 12;9 P 2 Q 5 = 6 → 9 + 2 - 5 = 6;Similarly, 21 P 11 Q 9 = 21 + 11 - 9 = 23.Hence, 23 is the correct answer.