It is 2:10 you have to be home by half past 5. How long before you have to be home

3 hours 20 minutes before you have to be home

60 minutes in an hour

Half past 5 = 5:30

This is how I do it - if you add 50 minutes to 2:10 you get to 3:00, so now you can make it easier to get to 5:30, which is 2:30

Add the 50 on to the 2 hours and 30 minutes to get 3 hours and 20 minutes.

3:20 is your answer