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_7, x_7 will play squash and x_7 is a taxi driver. For all x_7, x_7 will play squash if and only if x_7 is a mechanic.
For all x_7, x_7 will play squash can be inferred via the universal simplification rule. For all x_7, x_7 is a taxi driver can be inferred via the universal simplification rule. For all x_7, if x_7 plays squash, then x_7 is a mechanic can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 were a mechanic, then x_7 is playing squash can be inferred via the universal biconditional elimination rule.