Backing question...

[Spidey44]

Ok, here's another question...If say your backer gives you a full buy in, but you go into your own pocket to top yourself off a couple times say an extra 50 on top of the original 100 so total buy ins = 150 and you end up with the same 300? So You're up 150 total.

[Talking Poker]

So he gave you $100, you used another $50 from your own pocket (by choice, and not per your agreement with him), and you ended up with $300?

I'd say you own him (his) $100 + $75 (50% of 150) = $175.