Alright, so the first thing I would do is find the LCM of the dividends, which is 20. So we have 10 15/20 and 6 16/20. You can either leave it there and just carry the one (20 in this case) for 3 19/20. If you multiply 10 by 20 and add 15, or 6 by 20 and add 16 (which I think is easier) you get 215/20 - 136/20 = 79/20. It can be simplified from here if you teacher wants it in the future.
