From the periodic table:
mass of H = 1 gram
mass of C = 12 grams
mass of Cl = 35.5 grams
Therefore,
mass of CHCl3 = 12+1+3(35.5) = 119.5 grams
3Cl = 3(35.5) = 106.5 grams
This means that each 119.5 grams of CHCl3 contains 106.5 grams of Cl. To know the mass of Cl present in 38.3 grams of CHCl3, all you have to do is cross multiplication as follows:
mass of Cl = (38.3*106.5) / (119.5) = 34.1334 grams