Consider the following premises. If Robert goes running, then Robert is a lawyer. If Robert goes running, then Jessica is not making tea. Robert is a lawyer if and only if Robert is running. Jessica is making tea. Can we infer the following from them? If we can, name the inference rule being used: Robert is not a lawyer.
 From the fact that Robert is a lawyer if and only if Robert is running we can infer that if Robert were a lawyer, then Robert is running via biconditional elimination. From the fact that if Robert goes running, then Robert is a lawyer, and that if Robert were a lawyer, then Robert is running we can infer that Robert is running if and only if Robert is a lawyer via biconditional introduction. From the fact that if Robert goes running, then Jessica is not making tea, and that Jessica is making tea we can infer that Robert is not running via modus tollens. Finally, from the fact that Robert is running if and only if Robert is a lawyer, and that Robert is not running we can infer that Robert is not a lawyer via biconditional elimination. Therefore, the answer is yes.