What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_5, if x_5 were poor, then x_5 is writing a letter. For all x_5, x_5 is poor. For all x_5, x_5 will write a letter if and only if x_5 is sad.
For all x_5, x_5 will write a letter. For all x_5, if x_5 writes a letter, then x_5 is sad. For all x_5, if x_5 were sad, then x_5 is writing a letter.