## Thinking Mathematically (6th Edition)

The symbolic form of the provided argument is\begin{align} & \,\,\,\,\,\,\,\,\,\,p\to q \\ & \frac{\,\,\,\,\,\,\,q\to r}{\therefore \,\,\ \sim p\to \sim r} \\ \end{align}. It is an invalid argument, where, p is I am at the beach, q is I swim in the ocean and r is I feel refreshed.