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 x_10 is rich if and only if x_10 will drive a car. For all x_10, if x_10 takes a plane, then x_10 is rich. For all x_10, x_10 will take a plane or x_10 will drive a car. For all x_10, if x_10 were rich, then x_10 is taking a plane.
For all x_10, x_10 will take a plane if and only if x_10 is rich can be inferred via the universal biconditional introduction rule. For all x_10, x_10 is rich if and only if x_10 will take a plane can be inferred via the universal biconditional introduction rule. There is at least one x_10 for which if x_10 were rich, then x_10 is driving a car can be inferred via the existential biconditional elimination rule. There is at least one x_10 for which if x_10 drives a car, then x_10 is rich can be inferred via the existential biconditional elimination rule.