This would depend on what you are asking for.
If you are adding the two numbers(which the word and is implying) you’re answer is 25 1/4.
You get this by finding a common denominator. In this case, that can be 4.
Turn 1/2 in to 2/4.
Next, you add 11 and 13 to get 24.
Then, you’ll add 2/4 and 3/4. You will get 1 1/4
Add 24 and 1 1/4. You have your answer of 25 1/4