Solution:The pattern followed here is :(1st number) × 3 = (2nd number + 3rd number)
(13, 18, 21) → 13 × 3 = (18 + 21) = 39
(11, 25, 8) → 11 × 3 = (25 + 8) = 33
Similarly,
(14, 33, 9) → 14 × 3 = (33 + 9) = 42
Hence, (14, 33, 9) is the correct answer.