Tony finishes baking cookies at 10: 33 am he started at 7: 18 am now long was he baking cookies?

To find the amount of time between two events, we can use subtraction, just like we do with regular subtraction problems. The subtraction will look something like this:

  10:33
-
  7:18

Like in a regular subtraction problem, we can subtract the digits that line up, like 10 and 7. Subtracting all of the corresponding digits, we get that it took Tony 3 hours and 15 minutes to finish baking the cookies. 

Tong took 3 hours and 15 baking cookies