Consider the following premises. For all x_8, if x_8 makes tea, then x_8 is a mechanic. If John makes tea, then John is a mechanic. For all x_8, if x_8 were a mechanic, then x_8 is making tea. Can we infer the following from them? If we can, name the inference rule being used: If is not true that John is a mechanic if and only if John is making tea.
That contradicts the premises. Therefore the answer is no.