This is the part that usually trips people up on tests. When is followed by the masculine article el , they must smush together into one word: del . Incorrect: Es el libro de el chico. Correct: Es el libro del chico.
Answer: La computadora es de ellos.
, this usually involves two parts: identifying the owner using ser + de and then replacing that relationship with a possessive adjective (like su or sus ). p219 estructura 1 de quien es practice it top