Consider the following premises. For all x_5, if x_5 plays squash, then x_5 is a musician. For all x_5, if x_5 climbs a mountain, then x_5 is a musician. For all x_5, x_5 will climb a mountain or x_5 will take a plane. For all x_5, if x_5 takes a plane, then x_5 is playing squash. Can we infer the following from them? If we can, name the inference rule being used: For all x_5, x_5 is a musician or x_5 will drink water.
 From the fact that for all x_5, if x_5 takes a plane, then x_5 is playing squash, and that for all x_5, if x_5 plays squash, then x_5 is a musician we can infer that for all x_5, if x_5 takes a plane, then x_5 is a musician via universal transitivity. From the fact that for all x_5, if x_5 climbs a mountain, then x_5 is a musician, that for all x_5, if x_5 takes a plane, then x_5 is a musician, and that for all x_5, x_5 will climb a mountain or x_5 will take a plane we can infer that for all x_5, x_5 is a musician via universal disjunction elimination. Finally, from the fact that for all x_5, x_5 is a musician we can infer that for all x_5, x_5 is a musician or x_5 will drink water via universal addition. Therefore, the answer is yes.