What is the sum of the series \(12, 2, 15, -1, 18, -4, 21, -7, \ldots, 30?\)

[VJesus12]

What is the sum of the series \(12, 2, 15, -1, 18, -4, 21, -7, \ldots, 30?\)

A. 74
B. 84
C. 94
D. 104
E. 114

Answer: E

Source: e-GMAT