Consider the following premises. For all x_6, if x_6 were happy, then x_6 is fast. There is at least one x_6 for which x_6 will write a letter. For all x_6, if x_6 were an electrician, then x_6 is fast. For all x_6, x_6 is an electrician or x_6 is happy. Can we infer the following from them? For all x_6, x_6 is not fast.
That contradicts the premises. Therefore the answer is no.