Consider the following premises. For all x_18, x_18 will sleep. For all x_18, if x_18 were rich, then x_18 is making tea. There is at least one x_18 for which x_18 is a mechanic if and only if x_18 will sleep. For all x_18, x_18 is not a mechanic. Can we infer the following from them? There is at least one x_18 for which x_18 will make tea.
 From the fact that for all x_18, x_18 will sleep we can infer that for all x_18, x_18 will sleep or x_18 is rich. From the fact that there is at least one x_18 for which x_18 is a mechanic if and only if x_18 will sleep, and that for all x_18, x_18 is not a mechanic we can infer that there is at least one x_18 for which x_18 will not sleep. From the fact that for all x_18, x_18 will sleep or x_18 is rich, and that there is at least one x_18 for which x_18 will not sleep we can infer that there is at least one x_18 for which x_18 is rich. Finally, from the fact that for all x_18, if x_18 were rich, then x_18 is making tea, and that there is at least one x_18 for which x_18 is rich we can infer that there is at least one x_18 for which x_18 will make tea. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.