The balanced chemical reaction will be:
C3H8 + 5O2 = 3CO2 +4H2O
We are given the amount of propane gas to be burned. This will be our starting point.
55.9 g C3H8 ( 1 mol C3H8 / 44.1 g C3H8 ) ( 5 mol O2/1 mol C3H8)(32 g O2 / 1 mol O2) = 202.81 g O2