What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? William is reading a book if and only if Sarah is playing a game. If Thomas were a mechanic, then William is reading a book. For all y, if y plays a game, then y is a bartender. Sarah is not a bartender.
If William reads a book, then Sarah is playing a game. If Sarah plays a game, then William is reading a book.