How many moles are present in 18.4g of CaCl2?

By definition, one mole would be the same as the molecular mass. You take the number of moles and multiply it by the molecular mass. So if you have just 1 mole, the number of grams will be the added atomic masses of the elements in the compound.

Ca- 40.08

Cl- 35.5

CaCl- 75.6 grams