11 8/18 плюс 13 9/18

To add the two fractions, you need to first make sure they have a common denominator. In this case, the denominators are already the same, which is 18.

So, the sum is:

11 8/18 + 13 9/18 = (11 + 13) + (8/18 + 9/18) = 24 + 17/18 = 24 17/18

Therefore, the result of the sum is 24 17/18.