Consider the following premises. For all x_7, if x_7 were a sailor, then x_7 is climbing a mountain. For all x_7, x_7 is a janitor if and only if x_7 will climb a mountain. For all x_7, x_7 is a janitor or x_7 is a sailor. For all x_7, x_7 will drive a car. Can we infer the following from them? If we can, name the inference rule being used: For all x_7, x_7 will drive a car and x_7 will climb a mountain.
 From the fact that for all x_7, x_7 is a janitor if and only if x_7 will climb a mountain we can infer that for all x_7, if x_7 were a janitor, then x_7 is climbing a mountain via universal biconditional elimination. From the fact that for all x_7, if x_7 were a janitor, then x_7 is climbing a mountain, that for all x_7, if x_7 were a sailor, then x_7 is climbing a mountain, and that for all x_7, x_7 is a janitor or x_7 is a sailor we can infer that for all x_7, x_7 will climb a mountain via universal disjunction elimination. Finally, from the fact that for all x_7, x_7 will drive a car, and that for all x_7, x_7 will climb a mountain we can infer that for all x_7, x_7 will drive a car and x_7 will climb a mountain via universal conjunction. Therefore, the answer is yes.