# Cards!

Logic Level 3

Say we have a deck of 14 cards. They have a letter on one side, and a number on the other. Face up, they are: $1,2,3,4,5,6,7,A,B,C,D,E,F,G.$ Let's propose that on the back of any vowel card, there must be a prime. Find the minimum number of cards that must be flipped over to guarantee the validity of this statement.

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