What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_6, if x_6 were sad, then x_6 is a cashier. For all x_6, if x_6 reads a book, then x_6 is sad. There is at least one x_6 for which x_6 will read a book if and only if x_6 is a cashier.
For all x_6, if x_6 reads a book, then x_6 is a cashier. There is at least one x_6 for which if x_6 reads a book, then x_6 is a cashier. There is at least one x_6 for which if x_6 were a cashier, then x_6 is reading a book.