@Bmariachi01 Flip the sufficient and necessary and Negate both!

For example: All people who eat leftover egg salad will get food poisoning.

Eat leftover egg salad---> will get food poisoning

flip and negate ( reverse and do the opposite, if positive then negative or if negative then positive)

Contrapositive: Will not get food poisoning---> No (doesn’t) eat leftover egg salad.