Consider the following premises. For all x_7, if x_7 were an office clerk, then x_7 is a mechanic. For all x_7, if x_7 were happy, then x_7 is an office clerk. There is at least one x_7 for which if x_7 were a mechanic, then x_7 is an office clerk. Can we infer the following from them? There is at least one x_7 for which if x_7 were happy, then x_7 is a mechanic.
 From the fact that for all x_7, if x_7 were an office clerk, then x_7 is a mechanic, and that there is at least one x_7 for which if x_7 were a mechanic, then x_7 is an office clerk we can infer that there is at least one x_7 for which x_7 is an office clerk if and only if x_7 is a mechanic. From the fact that there is at least one x_7 for which x_7 is an office clerk if and only if x_7 is a mechanic we can infer that there is at least one x_7 for which if x_7 were an office clerk, then x_7 is a mechanic. Finally, from the fact that for all x_7, if x_7 were happy, then x_7 is an office clerk, and that there is at least one x_7 for which if x_7 were an office clerk, then x_7 is a mechanic we can infer that there is at least one x_7 for which if x_7 were happy, then x_7 is a mechanic. Therefore, the answer is yes.