15- 8 and 2/3. First, rewrite 8 and 2/3 as an improper fraction. To find the numerator, multiply 8 by 3 and add the 2. The improper fraction is 26/3. Now, write 15 with a denominator of 3. To do this, multiply 15 by 3/3, and get 45/3. Now you have 45/3-26/3. Subtract the numerators only to get 19/3. By lond division, you can rewrite this as a mixed number to get 6 and 1/3.
I hope this helps you. Good luck. :)