What is the sum of the first 12 terms of an arithmetic progression if the first term is -19 and last term is 36?

Answer: Option C

First term of AP = a = -19 and last term = l = 36
Number of terms = n = 12
$$\begin{array}{rl}& \text{Sum of AP}=\frac{n}{2}\left(a+l\right)\\ & =\frac{12}{2}\left(-19+36\right)\\ & =17\times 6\\ & =102\end{array}$$