How to add moving average trendline for summation of 2 data series

Hi all,

I have 3 data series in my pivot table namely Administrative, Sustaining, Projects.
I know how to add moving average trend line for each of them separately but I dont know
how to add moving average trend line for Administrative+Sustaining. that is I have to sum the
two data series and show moving average trend line in the chart.

Can anyone help me?

Excel's built in charts are not very smart, and don't do very much "automatically." In this case, if you want a plot and trendline for adm+sus, you will need to create a column/row in the spreadsheet that uses the =sum() function to create the sum, then add that column/row to the chart. Then the chart can do the moving average trendline for the sum.