But the first two square roots can be simplified since they have a perfect square factor in the radicand. ("Radicand" is the name for the expression inside a radical.)
which simplifies to:
Now that the radicals are simplified, we can see that the first two terms are like terms. (Like radical terms have the same type of root and the same radicands.) So we can subtract them. Exactly like 20x - 15x = 5x:
This is as far as we can go.