Answer : 1. "15"
Explanation :

Answer: A) 15 Explanation: Two series alternate here, with every third number following a different pattern.In the main series, 4 is added to each number to arrive the next.In alternate series, 5 is subtracted from each number t arrive the next number.Here in the main series 3 + 4 = 77 + 4 = 1111 + 4 = 1515 + 4 = 19 In alternate series 24 - 5 = 1919 - 5 = 14...