Translate the following inference to logic notation: Sarah is a doctor if and only if John is a cashier. For all x, if x_21 reads a book, then x_21 is a doctor. If Sarah were a doctor, then Sarah is reading a book. If it snows, then Sarah is reading a book. John is not a cashier. Therefore it is not snowing.
P(a) <-> p. forall x: Q(x) -> P(x). P(a) -> Q(a). q -> Q(a). ~p. Therefore ~q.