arithmetic seqeuences

The formula is $S_{n}=\frac{(T_1+T_n)n}{2}$. Note that t_12=(26+2)-(2*12)=28-24=4. Note that t_1=26. So we have $S_{12}=\frac{(4+26)12}{2}=\frac{30*12}{2}=30*6=\boxed{180}$