In this unbalanced chemical reaction, on the left side, there are:
1) three hydrogen atoms, one in molecule HBr and two in two molecules of sodium hydroxide (NaOH).
2) one bromine atom (Br) in hydrobromic acid (HBr).
3) two sodium atoms (Na) in two molecules of NaOH.
4) two oxygen atoms in two melecules of sodium hydroxide.
