What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_12, if x_12 were a cashier, then x_12 is not writing a letter. If Linda were a doctor, then Joseph is a server. For all x_12, x_12 will write a letter. Joseph is a server if and only if Linda is a cashier.
If Joseph were a server, then Linda is a cashier. If Linda were a cashier, then Joseph is a server. For all x_12, x_12 is not a cashier.