first you need to determine the molar mass of CaCl2
Molar mass of Ca=40.078
Molar mass of Cl=35.453 (multiply by 2 since there is 2 chlorines) =70.906
Add these together
Molar Mass if CaCl2 = 110.98
Divide mass of Calcium by Mass of CaCl2 and times by 100 (40.078/110.98)100=36.11 percent Calcium in CaCl2