Propane is a hydrocarbon and it will burn in presence of oxygen (it will undergo combustion) to give carbon dioxide and water (all in gas phase).
In presence of oxygen the carbon gets oxidized to carbon dioxide and hydrogen to water.
The general equation for a hydrocarbon undergoing combustion is

Here we are studying the combustion of propane so
x = 3
y = 8
Propane has molecular formula of C3H8
Therefore the balanced equation will be

Or
