If Charlotte started her homework at 9:15 and finished in 7 hours and a half what time would it be?

To make this easier for us lets first add as many hours needed to get to 12:15.

12-9 = 3

7:30 - 3:00 = 4:30

Now that we are at 12:15 we just add the remainder of the time.

12:15 + 4:30 = 4:45

remember we are dealing with time so after 12 comes 1 unless you are using military time.

It would be 4:45

You just can count on your fingers and the result at 7th finger will be 16=4 pm and to 15 add 30 su you will get 16:45