Start in this way. Calculate the amount of hydrogen, what you have in the 8.19 g water and the carbon what is in 20.2 g carbon dioxide.
Ratio calculation. m1xM1= m2/yM2
m1,2 mass
M1,2 molecular mass
x,y coefficients = how many atoms in the calculated molecule. For example water has 2 H and x for H is 2.
If you have this two masses, then you can subtract it from the given mass of the compound to get the amount of oxygen.
The next step is to conwert all masses into mol
You will get a mol ratio C:H:O
The carbon you set to 1 and calculate the other two elements. If still abroken number multiply so often until all numbers not broken anymor.