Demand Score and Project Score are calculated as:

Project / Demand Score = (10-risk_score + value_score + size_score) / 3

If you want to know how the risk_score, value_score and size_score are calculated in a demand please read this article

If you want to know how the risk_score, value_score and size_score are calculated in a project please read this article

Demand and Project Score are calculated using the Business Rules: “Compute Overall Score” for Demand/Project this business rule is calling updateOverallScore on EntityScorer Script Include that calculate risk as 10-risk (line 40)

In calculateScore on ScoreCalculator Script Includes the score is calculated as: (risk+size+value) / 3