Use a contraposition proof to prove that if $\sqrt{x}$ is irrational then $x$ is irrational. 

Use a contrapositive proof to prove that:

Given that $n$ is an integer, if $3n+2$ is even, then $n$ is even.

Use a contrapositive proof to prove that if $x$ is irrational then ${\displaystyle \frac{1}{x}}$ is irrational. 

Use a contrapositive proof to prove that if $5n+3$ is odd then $n$ is even.