Consider the following premises. For all x_10, if x_10 were an office clerk, then x_10 is a musician. It is snowing or Robert is an office clerk. It is snowing if and only if Robert is a musician. Can we infer the following from them? If we can, name the inference rule being used: Robert is not a musician.
 From the fact that for all x_10, if x_10 were an office clerk, then x_10 is a musician we can infer that if Robert were an office clerk, then Robert is a musician via universal instantiation. From the fact that it is snowing if and only if Robert is a musician we can infer that if it snows, then Robert is a musician via biconditional elimination. Finally, from the fact that if it snows, then Robert is a musician, that if Robert were an office clerk, then Robert is a musician, and that it is snowing or Robert is an office clerk we can infer that Robert is a musician via disjunction elimination, which contradicts that Robert is not a musician. Therefore, the answer is no.