The answer to that would be 15 13/30. You have to change the denominators, as well as the numerators, to fit both fractions. I did 10 * 3 = 30 & 15 * 2 = 30. That resulted in me getting 3 * 3 = 9 + 2 * 2 = 4, which equals 13.
I hope this answer helped you! If you have any further questions or concerns, feel free to ask! :)