Im going to assume that by fix, you mean install? Well, I'm personally not a fan of rides with floor rattling sound systems.
But for what it's worth, I believe mos people install their Subs into sub boxes, usually sold wherever you bought your subs, and then install those in their trunk, same goes for amps, they usually go upside down and out of the way inside the trunk...at least thats how it's installed on my Jetta (my only car with an amp) "How many amps"? lol, jeez bud, well, I'd say one...maybe a big one?