Consider the following premises. For all x_4, x_4 is an office clerk. If David were an office clerk, then it is windy. If David were a carpenter, then it is windy. Can we infer the following from them? If we can, name the inference rule being used: It is not windy.
 From the fact that for all x_4, x_4 is an office clerk we can infer that for all x_4, x_4 is an office clerk or x_4 is a carpenter via universal addition. From the fact that for all x_4, x_4 is an office clerk or x_4 is a carpenter we can infer that David is an office clerk or David is a carpenter via universal instantiation. Finally, from the fact that if David were an office clerk, then it is windy, that if David were a carpenter, then it is windy, and that David is an office clerk or David is a carpenter we can infer that it is windy via disjunction elimination, which contradicts that It is not windy. Therefore, the answer is no.