Answer: 9 13/28
Explanation:
First turn your mixed numbers into improper fractions. 6 3/4 becomes 27/4 and 2 5/7 becomes 19/7. Now we need to make the denominators match. The least common multiple of 7 and 4 is 28. 27/4 becomes 189/28 and 19/7 becomes 76/28. We can now add these to get 265/28. This improper fraction can now be turned back into a mixed number. 28 will go into 265 evenly 9 times with 13 left over. Answer is 9 13/28