Translate the following inference to logic notation: If it rains, then it is cloudy. If Susan writes a letter, then it is raining. If it is late, then it is snowing. If it snows, then Elisabeth is driving a car. If it is cloudy, then it is late. Therefore if Susan writes a letter, then Elisabeth is driving a car.
p -> q. r -> p. s -> t. t -> u. q -> s. Therefore r -> u.