Nute Dosage Question

I recently purchased some "miracle gro liqua feed bloom booster" from walmart. The numbers on it are 12nitrogen-9phosphate-6potass. I'm wondering if anyone can give me any kind of rough idea of how much i should use on my plants. Or how much i should roughly mix in a gallon of water. Thanks!

Damn, does anyone have any idea? I know this is kind of a hard question to answer, but I'd just need a rough range and I can slowly increase and see what happens.