how to do some calculations depending on date picker selection?

Hello,

I have a simple table (=result of doing some operations in a data feed), where I need to calculate a quotient that depends on a selected date (by date picker) in my mashup.

The table is shown on the left, the number of lines is not fix. There are also bar charts in my mashup where the computed sum controlled by the selected date is shown. This works fine with the filter and so on...

Now I want to display the result (tacho, text, ...) of some calculations like the one shown in the next picture:

Any suggestions how to do this with Mashzone? Thanks in advance