It's quite straight forward samxixix,
BUY currently own 75%, Advent 25%. BUY pays nothing for the first drill which Advent are paying $24mil for so BUY are free carried on this first drill. After the first drill, BUY drop to 15%, Advent rise to 85%. BUY then has to pay 15% of any further exploration in the area. They don't have to declare anything until it happens. BUY will be 15% after the first drill, that's all you need to know.
