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 is a taxi driver if and only if x_7 will drink water. If Susan were a taxi driver, then Susan is drinking water.
For all x_7, if x_7 were a taxi driver, then x_7 is drinking water can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 drinks water, then x_7 is a taxi driver can be inferred via the universal biconditional elimination rule.