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: For all x_12, if x_12 were happy, then x_12 is driving a car. If Thomas doesn't drive a car, then Jessica is a nurse. For all x_12, if x_12 drives a car, then x_12 is happy. Thomas is not happy.
For all x_12, x_12 is happy if and only if x_12 will drive a car can be inferred via the universal biconditional introduction rule. For all x_12, x_12 will drive a car if and only if x_12 is happy can be inferred via the universal biconditional introduction rule.