Translate the following inference to logic notation: If Elisabeth drives a car, then David is an office clerk. If David were an office clerk, then Patricia is sad. Linda is a soldier if and only if Patricia is sad. David is not an office clerk. If Patricia were sad, then it is late. If it is late, then Elisabeth is driving a car. Therefore Linda is not a soldier.
p -> q. q -> r. s <-> r. ~q. r -> t. t -> p. Therefore ~s.