I am assuming your question should be formatted as follows:
9(sqrt(2)) + 5(sqrt(3))
We want to try make the roots have the same numer in them, we would usually do this by moving numbers outside the sqrt to the inside and finding factors of them both that are square numbers, but I can see that that will not work for this question with numbers that I can do in my head. If you know all your square numbers and their multiples by heart then you might be able to solve this. But for us mortals it is time to pull out the calculator.
21.388176