What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: There is at least one x_10 for which if x_10 were a sailor, then x_10 is a cashier. For all x_10, x_10 will take a plane if and only if x_10 will listen to a song. For all x_10, x_10 will not listen to a song. For all x_10, x_10 will take a plane if and only if x_10 is a sailor. For all x_10, if x_10 were a cashier, then x_10 is a sailor.
There is at least one x_10 for which x_10 is a sailor if and only if x_10 is a cashier can be inferred via the existential biconditional introduction rule. There is at least one x_10 for which x_10 is a cashier if and only if x_10 is a sailor can be inferred via the existential biconditional introduction rule. For all x_10, if x_10 takes a plane, then x_10 is listening to a song can be inferred via the universal biconditional elimination rule. For all x_10, if x_10 takes a plane, then x_10 is a sailor can be inferred via the universal biconditional elimination rule. For all x_10, if x_10 listens to a song, then x_10 is taking a plane can be inferred via the universal biconditional elimination rule. For all x_10, if x_10 were a sailor, then x_10 is taking a plane can be inferred via the universal biconditional elimination rule. For all x_10, x_10 will not take a plane can be inferred via the universal biconditional elimination rule.