burn down chart formula help

[nam]

i have a total value for 6 months of 900, then i have monthly values month1:10, month2:20, Month3:20, ... etc. 

what i want to show on a graph is a decreasing value so month1: 900-10, month2:900-10-20, Month3:900-10-20-20 and so on. so the graph starts with the total at the first month and with each month the graph decreases. the formula im using is =TotalMS-rangesum(Above(sum(MileSBL))). the dimension on the graph is YearMonth.

Please help

[nam · Accepted solution]

rangesum(Above(sum(TotalMSBL)0,rowno()))

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