Hardness is sum of all divalent cations (meaning all species with a positive charge of 2) in a water sample. Magnesium (Mg2+) and calcium (Ca2+) are the most common divalent cations that contribute to hardness. For a groundwater sample containing 100 mg/L Ca2+ and 10 mg/L of Mg2+, express the sample's hardness in meq/L and mg/L of CaCO3.