k2 are the variable costs of the two outputs which need to be determined. kI represents the known variable costs of the input. Kvar denotes the respective sum of the variable costs. a1 and a2 are the allocation factors for the respective output, i.e. they describe the proportion of the input that is assigned to a co-product. The weighting keys are f1 and f2: This results in specific variable costs k1 and k2: According to the introducing relation of the cost allocation, the following applies: Further reading Günter Wöhe: Einführung in die allgemeine Betriebswirtschaftslehre (DE: Introduction in general business economics). 18th edition. Vahlen, München 1993, . See also Cross-multiplication (or rule of proportion) Cost allocation References Accounting