Consider the following premises. For all x_12, if x_12 makes tea, then x_12 is a cashier. For all x_12, x_12 is a sailor if and only if x_12 is a cashier. There is at least one x_12 for which x_12 will make tea or x_12 is not a sailor. Can we infer the following from them? If we can, name the inference rule being used: For all x_12, if is not true that x_12 is a cashier if and only if x_12 is a sailor.
That contradicts the premises. Therefore the answer is no.