Item 3.3.5.a.
Negation: The power goes off and the food does not spoil.
Converse: If the food spoils, then the power went off.
Contrapositive: If the food does not spoil, then the power did not go off.
Negation: The power goes off and the food does not spoil.
Converse: If the food spoils, then the power went off.
Contrapositive: If the food does not spoil, then the power did not go off.