This equation seems completely balanced to me. Let's figure out if this is true.

For an equation to be a balanced one, the quantity of atoms of each type must be the same on the left side and on the right side. Do not forget that an index `n` under atom in a formula means that this molecule has `n` atoms of that type.

There are three types of atoms in our reaction: `C,` `H,` and `O.` Let's start from `O.`

There are `0` oxygen atoms in `CH_4,` `2*2` oxygen atoms in two molecules of `O_2,` `2` in `CO_2` and `2` in two molecules of `H_2O.` So, we have `0 + 2*2 = 4` oxygen molecules at the left side and `2 + 2 = 4` at the right one. Balanced.

For `C,` we have `1 + 0 = 1 + 0,` also true. For `H,` `4 + 0 = 0 + 2*2,` true. As a whole, the equation is balanced.