Measure for Percentage difference

Zaynah16 I'm not sure what do you mean by 'percentage total score' 🙂
Anyway I took a guess, maybe this will anyway show you the way:

_Measure = 
VAR _pct_on_track = 
DIVIDE(
	CALCULATE(
		SUM(RAG status[Score]),
		RAG status[Status] = "On Track"
	),
	CALCULATE(
		SUM(RAG status[Score]),
		REMOVEFILTERS(RAG status[Status])
	)
)
VAR _pct_at_risk = 
	DIVIDE(
		CALCULATE(
			SUM(RAG status[Score]),
			RAG status[Status] = "At Risk"
		),
		CALCULATE(
			SUM(RAG status[Score]),
			REMOVEFILTERS(RAG status[Status])
		)
	)
RETURN
	_pct_on_track - _pct_at_risk

      

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