Strategy for the Combustion Train Problem

Because the compound is a hydrocarbon, we know that it is made only of carbon and hydrogen. The carbon in the CO₂ and the hydrogens in the water must come from the compound. This means the amount of carbon in CO₂ is equal to the amount of carbon in the hydrocarbon.
Similarly all the hydrogen in the H₂O that is formed is from the hydrocarbon.
With the skills you gained in the last section dealing with Moles you should be able to determine the number of moles of carbon and hydrogen from the masses of CO₂ and H₂O produced.
From there just proceed as you did in Example 2.