What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Barbara drives a car, then Patricia is a poet. Barbara is driving a car if and only if Mary is drinking water. For all x_20, if x_20 writes a letter, then x_20 is drinking water. If Patricia were a poet, then Mary is writing a letter.
If Barbara drives a car, then Mary is writing a letter. If Barbara drives a car, then Mary is drinking water. If Mary drinks water, then Barbara is driving a car.