ThatA only
A only
I'd say cards 1 and 3 because we have to determine if the rule has been followed. We know those two have a letter or even number, if they don't have the same on the back then the rule is broken.
I say 2 cards because the questions stipulates card(s)
Doesn't 7 need turning over too in case it has a vowel on the other side- meaning the rule hasn't been applied ?
A & 7
First (A) and last (7) I think.
The card with A must have an even number on the reverse because A is a vowel
The card with K - Don't care it's not a vowel - the rule is not broken with an odd or even number
The card with 2 on - it doesn't matter as it can have vowel or consonant and the rule is still true
The card with 7 - Must be viewed to check the reverse is not a vowel - otherwise the rule is not followed