Final answer:
The subject of the sentence is 'majority', as it is the main focus of what is being described in the sentence.
Step-by-step explanation:
The subject in the sentence "The majority of working teens are employed by restaurants, grocery stores, and department stores" is 'majority'. This is because the sentence describes what the majority is doing, which makes 'majority' the main focus of the sentence. In this context, 'working teens', 'employed', and 'restaurants, grocery stores, and department stores' are not the subject, but rather, 'working teens' is the prepositional phrase modifying 'majority', 'employed' is the main verb, and 'restaurants, grocery stores, and department stores' is the object of the preposition.