Step-by-step Solution:

\[ \text{Series: } 12,\; 24,\; 14,\; 28,\; 18,\; 36,\; ? \] \[ \text{Split into two sequences:} \] \[ \text{Odd positions: } 12,\; 14,\; 18,\; ? \] \[ \text{Even positions: } 24,\; 28,\; 36 \] \[ \text{Odd sequence differences:} \] \[ 14 - 12 = 2,\quad 18 - 14 = 4 \] \[ \text{Pattern: } +2,\; +4,\; +8 \] \[ \text{Next term} = 18 + 8 = 26 \] \[ \text{Even sequence (for verification):} \] \[ 28 - 24 = 4,\quad 36 - 28 = 8 \;(\text{doubling}) \] \[ \therefore \text{Next term in series} = \boxed{26} \]