284 g
First, lookup the atomic weights of all the elements involved.
Atomic weight of Calcium = 40.078
Atomic weight of Chlorine = 35.453
Now calculate the molar mass of CaCl2
40.078 + 2 * 35.453 = 110.984
Using that molar mass, calculate how many moles of CaCl2 you have.
445 g / 110.984 g/mol = 4.009586967 mol
Since each molecule of CaCl2 has 2 chlorine atoms, multiply the number of moles of CaCl2 by 2 to get the number of moles of Chlorine atoms.
4.009586967 * 2 = 8.019173935
And finally, multiply by the atomic weight of chlorine.
8.019173935 * 35.453 = 284.3037735
Since you have have 3 significant figures in your data, round the result to 3 significant figures, giving 284 grams.
