Calculate the percentage (%) by mass of magnesium in magnesium sulfate (MgSO4\text{MgSO}_4MgSO4). Give your answer to 3 significant figures. Relative atomic mass (ArA_rAr): Mg=24.3\text{Mg} = 24.3Mg=24.3. Relative formula mass (MrM_rMr): MgSO4=120.4\text{MgSO}_4 = 120.4MgSO4=120.4.