A magnesium-lead alloy of mass 5.5 kg consists of a solid α

A magnesium-lead alloy of mass 5.5 kg consists of a solid a phase that has a composition that is just slightly below the solubility limit at 200oC (390oF).
(a) What mass of lead is in the alloy?
(b) If the alloy is heated to 350oC (660oF), how much more lead may be dissolved in the a phase without exceeding the solubility limit of this phase?