Consider the following premises. For all x_5, if x_5 plays squash, then x_5 is fast. There is at least one x_5 for which x_5 will not play squash. For all x_5, if x_5 were fast, then x_5 is playing squash. Can we infer the following from them? For all x_5, x_5 is fast.
 From the fact that for all x_5, if x_5 plays squash, then x_5 is fast, and that for all x_5, if x_5 were fast, then x_5 is playing squash we can infer that for all x_5, x_5 will play squash if and only if x_5 is fast. From the fact that for all x_5, x_5 will play squash if and only if x_5 is fast we can infer that for all x_5, if x_5 were fast, then x_5 is playing squash. Finally, from the fact that for all x_5, if x_5 were fast, then x_5 is playing squash, and that there is at least one x_5 for which x_5 will not play squash we can infer that there is at least one x_5 for which x_5 is not fast, which contradicts that For all x_5, x_5 is fast. Therefore, the answer is no.