The only possible reaction for conversion of a hydrocarbon to carbon dioxide is combustion reaction
Combustion is burning of a substance in presence of oxygen
In case of sufficient supply of oxygen the hydrocarbon converts to carbon dioxide and water.
The general reaction for combustion of any hydrocarbon will be
CxHy + (x + y/4)O2 (g) ---> xCO2(g) + y/2H2O
In the given problem we have propane and the balanced combustion equation will be
C3H8(g) + 5O2(g) ---> 3CO2(g) + 4H2O
As per equation , one mole of propane (molar mass 44g/mol) is required for production of three moles of carbon dioxide (molar mass 44 g/mol)
3 moles of carbon dioxide will weigh 3 X 44 = 132 g
So
132g of carbon dioxide need 44g of propane
1 g of carbon dixoide needs 44 / 132 g of propane
346g of carbon dioxide need = 44 x 346 / 132 g of propane = 115.33 g of propane