What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_7, x_7 is fast if and only if x_7 is a taxi driver. For all x_7, x_7 is a writer. For all x_7, x_7 is fast.
For all x_7, x_7 is a writer and x_7 is fast. For all x_7, x_7 is fast and x_7 is a writer. For all x_7, if x_7 were fast, then x_7 is a taxi driver. For all x_7, if x_7 were a taxi driver, then x_7 is fast.