Each of the 2 above expressions return 1-1 single value (e.g. 7,5 and 8,5) - and I want their avarage.
(((Rangesum is used only for this: if the denominator is zero, (sum of Measure 3+4) the Expressions returns null(). Rangesum turns it into a 0. But lets forget the rangesum, it is not relevant for my problem.)))