Answer:
They left the beach at 2:20pm
Explanation:
if they got there at 11:50am and spent 1hr and 20min swimming that would have put them at 1:20pm you then add the 30min they played volleyball which would put you at 1:50pm you then add the 35min they built sand castles for which would put you at 2:20pm. so they left the beach at 2:20pm