How to Minus graph ?

[hatman_nus]

Hi,

How to Minus graph ?

Example
i want to sum (A+B+C)-X-Z = new graph

Pleas help us to find best solution.
Thank you.

[gandalf]

Add all five data sources to the graph (you may choose a white color to make them disappear). Note their respective "letters" from "Graph Management" in DEBUG mode. Then, please prepare the CDEF required to do the math (see rrdtool manual on rrdtool website)
R.