Quote:

If a card has a vowel on one side, then it has an even number on the other side



If the 7 card has A, E, I, O, or U on the side that you can't see then there is a card which has a vowel on one side and an odd number on the other side which makes the statement false.

If the problem stated that these are the fronts of the cards and the statement said "If a card has a vowel on the front, then it has an even number on the back" you would be right, but it doesn't say that. Both sides are equally sides of the card