It is false that some rare coins are worthless collectibles. Therefore, it is false that all rare coins are worthless collectibles.
A) Invalid, illicit conversion.
B) Invalid, illicit subcontrary.
C) Invalid, illicit contrary.
D) Invalid, illicit subalternation.
E) Valid.

Question

Quizplus · Accepted Answer

This is a valid conversion of the original statement. If it is false that some rare coins are worthless collectibles, that means that there are rare coins that are valuable collectibles. Therefore, it cannot be true that all rare coins are worthless collectibles.

It Is False That Some Rare Coins Are Worthless Collectibles