To add mixed numbers, we first add the whole numbers together, which gives us 6 + 4 = 10. Then, we add the fractions together. The fractions 7/10 and 9/10 have the same denominator, so we can simply add the numerators: 7 + 9 = 16. Therefore, the sum of the fractions is 16/10. We can simplify this fraction by dividing both the numerator and denominator by their greatest common divisor, which is 2. This gives us 16/10 = 8/5. Putting it all together, the sum of the mixed numbers is 10 8/5. Simplifying the whole number and fraction part, we get 10 1 3/5, which is equivalent to 11 3/5.