Chapter 3.4, Problem 5PS

To determine

a)

Whether the argument $\begin{array}{l}p\to q\\ \underset{\_}{\sim q}\\ \therefore \sim p\end{array}$ is valid or invalid and gives reason for the answer.

To determine

b)

Whether the argument $\begin{array}{l}p\to q\\ \underset{\_}{q}\\ \therefore p\end{array}$ is valid or invalid and gives reasons for the answer.