Lesson 6 vamos a comer al aire libre unit test

Can somebody me out with this spanish question? completa la oración con la voz pasiva con se. used cars for sale. carros usados. (the answer is not usa los or venta de)

Usualmente ustedes juntos en la universidad. a. comes b. come c. comen d. comemos

Mary just sent out invitations to her wedding last week the invitations were so heavy that she put more than just one stamp on each envelope she used 255 stamps and mailed out 85 invitations and see you as an equal amount of stamps on each envelope