CH4+ (2)O2—CO2+ (2)H2O
1 C 1
4 H 2 > 4
4 < 2 O 3 > 4
You leave [C] alone and only focus on [O] and [H]
You’ll have to place 2 on the right side in front of H2O because there is a H4 on the left side
This makes H4 on the right side and O2 which then makes the total of [O] on the right side four
You then will need to place a 2 in front of O2 to make the total of [O] on the left side four as well
