Consider the following premises. Jennifer is an electrician if and only if Sarah is a mechanic. For all x_7, x_7 is a police officer if and only if x_7 is a mechanic. Sarah is not a police officer. Can we infer the following from them? Jennifer is an electrician.
 From the fact that for all x_7, x_7 is a police officer if and only if x_7 is a mechanic we can infer that Sarah is a police officer if and only if Sarah is a mechanic. From the fact that Sarah is a police officer if and only if Sarah is a mechanic, and that Sarah is not a police officer we can infer that Sarah is not a mechanic. Finally, from the fact that Jennifer is an electrician if and only if Sarah is a mechanic, and that Sarah is not a mechanic we can infer that Jennifer is not an electrician, which contradicts that Jennifer is an electrician. Therefore, the answer is no.