Determine the mass of the combustion of 50.0 g of C4H8. Please help ASAP!

write the balanced equation:

C4H8 + 6O2 >>>4CO2 + 4H2O
so the mole ration of butane to O2 is 1:4
moles of butane: 50/56
moles of O2=200/56
grams of O2=moles*32=200*32/54
total mass of combutsion=grams O2 + 50