How should this combustion reaction be balanced?

C5Hg + O2 → CO2 + H2O

Answer: 4 C5H + 21 O2 > 20 CO2 + 2 H2O

Explanation: there will be 4 moles of C5H, 22 moles of O2 and on the product side 20 moles of CO2 and 2 moles of water.

C atoms is 20 in both reactant and product side

H is 4 atoms each

O have 42 atoms each side.