Answer: de ida y vuelta, el anuncio, el equipaje, embarque
Explanation: Above is a list of the correct answer choices in the order that they fill in the blanks. The one item (escala) in the vocabulary terms list was not used in the four sentences. Translated, the passage should read as follows: I am going to Costa Rica on vacation, so I will buy a round-trip ticket (de ida y vuelta). The flight makes the announcement (anuncio) in Houston. When I arrive at the airport, I have to check in the baggage (facturar el equipaje). I have to find my flight gate (puerta de embarque).