Question

A substance is known to contain 2.00 g of carbon for every 5.33 g of oxygen. How many grams of carbon will be present in 55.0 g of this substance?

Answer 1

First, set up a proportion:
You have 2.00 g Carbon and 7.33 g of the total substance (find it by adding 2.00g C + 5.33 g O)
You have an unknown g carbon with 55.0 g o total substance.

So:
$\frac{2.00}{7.33} = \frac{x}{55.0}$

Multiply 2.00 by 55.0 and divide the answer by 7.33 
You'll get 20.63...

Answer 2

Answer : The mass of carbon present in 55.0 grams of the substance will be, 15.006 grams.

Explanation :

First we have to calculate the total mass substance.

Total mass of substance = Mass of carbon + Mass of oxygen

Total mass of substance = 2.00 g + 5.33 g = 7.33 g

Now we have to calculate the mass of carbon present in 55.0 grams of substance.

As, 7.33 grams of substance contain 2.00 grams of carbon.

So, 55.0 grams of substance contain $\frac{2.00}{7.33}\times 55.0=15.006$ grams of carbon.

Therefore, the mass of carbon present in 55.0 grams of the substance will be, 15.006 grams.