Adding Total line to Chart

[Icebun]

I have a line graph that plots one of 4 expenditur etypes by month.

Month is the x axis and expenditure values are plotted on the y axis.

There are 3 expenditure types (capital, pay, non pay and income) so I get 4 lines.

How can I add a line to show the net total of all 4 expenditure types.

For example, if Month 1 had the following values :

Pay 1000
Non Pay 1000
Capital 5000
Income -2000

I would want to plot a point at 500 on the y axis.

Regards,

 

[Icebun]

Apologies, the last line should read 5000.