Answer
Use letters to represent each simple statement in the argument.
p: He is intelligent.
q: He is an overachiever.
Express the premises and conclusion symbolically as:
\[\frac{\begin{align}
& p\vee q \\
& \tilde{\ }p \\
\end{align}}{\therefore q}\ \ \ \ \ \frac{\begin{align}
& \text{He is intelligent or an overachiever}\text{.} \\
& \text{He is not intelligent}\text{.} \\
\end{align}}{\therefore \text{He is an overachiever}\text{.}}\]
The argument is in the form of Disjunctive Reasoning.
Thus, the argument is valid.