Influence points, flipping

[Devlin]

Finally taking a break from Civ4 to try out GC2, I never played GC1. Going alright so far, but I'm currently attempting to flip an AI planet, and don't actually know what the numbers add up to

I know I need 4 times the influence to have a chance to flip it, but what exactly is that, here is the data:

The planet has an influence of 15. 10 from the planet, 3 from population, + -7 from improvements and misc. +2 from your influence ability & +7 from your civilization's influence.

So does this mean I have 9 influence there and they have 6, or I have 9 and they have 15, or this planet is never going to flip no matter what i do, and what can I do to flip this planet if it's possible?

The planet is class 13 with a pop of 4.47b (5b max currently, though with open space for farms and a 300% farm square if AI gets around to it) and approval rating of 82% if any of that matters.

[Peets]

the number between the () has to be 4 or higher to flip.

[Smokey the Pott]

I don't know what the math is, but I'm pretty sure a couple ships and troop transports costs less than a culture flip.

[Devlin]

Ha, it would be something obvious like the (), all those math classes useless again! Thanks Peets

And ya, I just seem to have this obsession with flipping, do it in Civ, too.