Write the Balanced Equation

Skeleton:
CH4 + O2 → H2O + CO2
I don't understand how to balance this

CH4 + O2 → H2O + CO2

This is an equatiion that can be balanced by inspection. That's just another way of saying we take a guess. But you don't guess just any numbers but make educated guesses. For example, I see 1 C on the left and 1 C on the right so let's leave that alone. Next I wee 4 H atoms on the left with CH4 so let's put a 2 in front of te H2O on the right which will give us 4 H atoms on the right like this.
CH4 + O2 → 2H2O + CO2
Next I notice there is just 1 O2 on the left but two places on the right for O. So it makes sense to me to count how many I need on the right. I see 2 O from 2H2O and I see 2 O from 1 CO2. That makes 4 O atoms we need on the left. Just place a two in front of the O2 like this.
CH4 +2O2 → 2H2O + CO2
Don't quit there.It is imperative that you check it to make sure there are the same number of atoms of each element on each side of the equation. If not you are not through.
CH4 +2O2 → 2H2O + CO2
1 C on left and right
4 H on left from CH4 and 4 on right from 2H2O
4 O on left from 2O2 and 4 on right from 2H2O and CO2.
Done.
There is another way to do this by using an oxidation/reduction method but this is the simple way.

Balanced equation:-

CH4+2O2---->Co2+2H2O

Balancing a chemical equation involves making sure that there are an equal number of atoms of each element on both sides of the equation.

Let's go step by step to balance the given equation:

1. Start by counting the number of atoms of each element on both sides of the equation:
C: 1 on the left, 1 on the right
H: 4 on the left, 2 on the right
O: 2 on the left, 3 on the right

2. Since there are more O atoms on the right side, we'll balance this element first. To balance the O atoms, we can place a coefficient of 2 in front of H2O, making the number of O atoms on both sides equal:
CH4 + O2 → 2H2O + CO2

3. Now let's balance the H atoms. Currently, there are 4 H atoms on the left and 4 H atoms on the right (2 in each water molecule). So, the H atoms are already balanced.

4. Finally, let's balance the C atoms. There is 1 C atom on the left and 1 C atom on the right. Therefore, the C atoms are already balanced.

The balanced equation is:
CH4 + O2 → 2H2O + CO2

In this balanced equation, there is now an equal number of atoms of each element on both sides.