Complex sentence: After operating costs are deducted (which in the past have averaged about 12% of turnover) the remaining money is distributed to the copyright holders (in the case of PRS, these are the songwriters or the publishers with whom they have agreements).
Split into simpler sentences: After operating costs are deducted (which in the past have averaged about 12% of turnover). The remaining money is distributed to the copyright holders (in the case of PRS, these are the songwriters or the publishers with whom they have agreements).