Geoffrey and his babysitter spent 20 minutes preparing dinner, 2 hours and 30 minutes playing board games, and half an hour making dessert. How many minutes did they spend doing these activities?

20 minutes is 20 minutes, and since there are 60 minutes in an hour and we have two hours, we have 60*2=60+60=120 and 120+30=150 minutes spent playing board games, so we have 150+20=170 minutes so far. I challenge you to figure out how many minutes are in half an hour and to add the rest up - good luck, and feel free to ask any further questions!