What is the contrapositve of if pi, the cat, is content, she is purring.

Let "Pi is content" be P and "She is purring" be Q.
This statement is "If P, Then Q"
The contrapositive is "If not Q, Then not P"
So, "If Pi, the cat, is not purring, then she is not content." is the contrapositive. 

"If Pi, the cat, is not purring, then she is not content."