[tex]\bf n^{th}\textit{ term of an arithmetic sequence}\\\\a_n=a_1+(n-1)d\qquad
\begin{cases}
n=n^{th}\ term\\
a_1=\textit{first term's value}\\
d=\textit{common difference}\\
----------\\
n=18\\
a_1=6\\
d=17
\end{cases}
\\\\\\
a_{18}=6+(18-1)(17)\implies a_{18}=6+(17)(17)
\\\\\\
a_{18}=6+289
\implies a_{18}=295[/tex]
