The contrapositive of the statement "If you will work, you will earn money" is ..... .

Let $\Delta, \nabla \in\{\wedge, \vee\}$ be such that $( p \rightarrow q ) \Delta( p \nabla q )$ is a tautology. Then

$\sim (p \Rightarrow q) \Leftrightarrow \sim p\; \vee \sim q$ is

$\sim (p \vee q) \vee (\sim p \wedge q)$ is logically equivalent to

The statement $\sim[p \vee(\sim(p \wedge q))]$ is equivalent to

Suppose $p, q, r$ are positive rational numbers such that $\sqrt{p}+\sqrt{q}+\sqrt{r}$ is also rational. Then