There are 3 parts of a radical. The radicand, which is the number that is being “rooted”, the index which is the power of what we are rooting by (such as cube root or square root), and finally the coefficient, which is the number outside of the root symbol in the equation.
The most important thing to remember when adding or subtracting radicals is that you can only do so with like terms. This means that the radicands and the indexes must be the same before you can add or subtract them. To do this, you must simplify the radical and if the radicands are the same number, you can add or subtract as you please like so: 
