Carbon tetrachloride has a chlorine-to-carbon mass ratio of 11.8: 1. if a sample of carbon tetrachloride contains 27 g of chlorine, what mass of carbon does it contain?

The ratio of Cl to C is 11.8:1
The mass of Cl present in the compound is 11.8 times the mass of carbon present.
If there’s 11.8 g of Cl - mass of C is 1 g
If there’s 1 g of Cl - mass of C is 1/11.8
Therefore when there’s 27 g of chlorine - mass of C is 1/11.8 x 27 = 2.29 g
When there’s 27 g of chlorine then mass of C present is 2.29 g

Answer is to avoid experimental error