What is the missing number in the following series - 13, 15, 26, 24, 37, 35, ?, 48

Answer 1

13 - 2 = 15
15 + (9+(2*1)) = 26
26 - 2 = 24
24 + (9+(2*2)) = 37
37 - 2 = 35
35 + (9+(2*3)) = 50
50 - 2 = 48.