A magnesium-lead alloy of mass 5.5 kg consists of a solid phase that has a composition

Question:

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