Rolling Value For Last 3 Months

Hi,

Try this approach

1. Create a Calendar Table with calculated column formulas for Year, Month name and Month number.  Sort the Month name by the Month number column
2. Create a relationship (Many to One and Single) from the Date column of the Fact table to the Date column of the Calendar table
3. To your visual, drag Year and Month name from the Calendar table
4. Write these measures

C = sum(Data[Cost])

T = sum(Data[Tonne])

CPT = divide([C],[T])

R3M C = calculate([C],datesbetween(calendar[date],edate(min(calendar[date]),-2),max(calendar[date])))

R3M T = calculate([T],datesbetween(calendar[date],edate(min(calendar[date]),-2),max(calendar[date])))

R3M CPT = divide([R3M C],[R3M T])

Hope this helps.