The following diagram represents the collection of co2 and h2o molecules formed by complete combustion of a hydrocarbon. (figure 1)

what is the empirical formula of the hydrocarbon?
express your answer as a chemical formula.

The answer is

A + B > CO2  + H2O
since it is combustion,  so B must be O2
A + O2 > CO2  + H2O
the form of A is A=CxHy
the number of C is 1 (CO2)
the numer of H is 2  (H2O)

the balanced equation is CH4 + 2O2 > CO2 + 2H2O
the empirical formula is CH4