I can't figure out the actual math for calculating dynamic pricing. If I was looking at a bundle of 3 books, how could I calculate what the bundle price would be if I bought one of the books outright? For example, if a bundle cost $15 for three books, and the books are normally priced at $10 each (amounting to $30 if I bought all three separate), then if I bought one of the books separate, I would think the bundle would cost $10 for the remaining two... as each would be 50% off in that bundle. but that math doesn't work. I've tried it on multiple bundles where I have some of the books, but not others.
So can anyone give us an actual formula for calculating dynamic pricing?