How many grams of Br are in 335g of CaBr2

The answer is 267.93 g

Molar mass of CaBr2 is the sum of atomic masses of Ca and Br:

Mr (CaBr2) = Ar (Ca) + 2Ar (Br)

Ar (Ca) = 40 g/mol

Ar (Br) = 79.9 g/mol

Mr (CaBr2) = 40 + 2 * 79.9 = 199.8 g/mol

The percentage of Br in CaBr2 is:

2Ar (Br) / Mr (CaBr2) * 100 = 2 * 79.9 / 199.8 * 100 = 79.98%

Now make a proportion:

x g in 79.98%

335 g in 100%

x : 79.98% = 335 g : 100%

x = 79.98% * 335 g : 100%

x = 267.93 g