To check if an equation is balanced, you should count the number of atoms of each element on both sides of the equation. If the number of atoms of each element is the same on both sides, then the equation is balanced.

For example, consider the following equation:

```

2H2 + O2 -> 2H2O

```

On the left side of the equation, we have 4 hydrogen atoms and 2 oxygen atoms. On the right side of the equation, we also have 4 hydrogen atoms and 2 oxygen atoms. Therefore, this equation is balanced.