Hola Alice
Your question certainly gave us a lot of discussion!
Actually, we often get questions about the differences between UK English and US English (to the point that we have a page on this very subject). Having surveyed the team and several independent American linguists everyone agreed that full board and half board exist and mean accomodation and meals, with "room and board" being synonymous with "full board" but that the terms full and half board are not common in the USA because the concept itself is pretty uncommon, indeed they all said that these terms are mostly encountered by Americans for the first time when they travel abroad.
Anyway, with this new knowledge I have included the translation of half board in the hint for that line of that challenge.
Thanks for getting in touch and helping us improve our exercises!
Saludos
Shui
