Consider the following premises. For all x_7, if x_7 plays squash, then x_7 is a musician. For all x_7, if x_7 were a musician, then x_7 is a nurse. For all x_7, x_7 is a nurse if and only if x_7 is sad. Can we infer the following from them? If we can, name the inference rule being used: For all x_7, if x_7 plays squash, then x_7 is a musician.
That is one of the premises. Therefore, the answer is yes.