It is given that "Jennifer is a juggler".
Since it is only stated that ''some magicians are jugglers", it implies that not all jugglers are magicians as there will be some jugglers who will not be magicians.
Hence, since Jennifer is a juggler, she may or may not be a magician.
It was given that "all magicians do card tricks"
Since Jennifer may or may not be a magician, it implies that: Jennifer may or may not do card tricks.
The conclusion that is logically valid is:
Jennifer may or may not do card tricks.