This document discusses phase diagrams and examples of using lever rule calculations to determine phase percentages and compositions. It provides an example phase diagram of the lead-tin system and asks questions about: 1) Solubility of tin in lead and lead in tin from the diagram 2) Using the Pb-10% Sn alloy and diagram to find phase percentages that form upon cooling 3) Masses of tin and lead in each phase for a Pb-10% Sn alloy cooled to 0°C