How to run 3 subs off my one amp...and is it possible?

Here is what I've got:

1. Rockford Fosgate R500-1 Prime 500 watt mono amp.
2. Hooked up to 2 Rockford Fosgate R1's (150 RMS each)
Now my other setup in my other vehicle...
1. Dual 400 watt max 2 channel amp
2.Hooked up to 1 Dual 12" (175 RMS)


SO... Could I somehow put all 3 subs onto just one of the amps? If so what one? Would it be pointless to do so? And would the quality be crappy?

If possible...I obvously know how to hook two subs up to an amp but I am unsure on how to hook up a third. I assume it would be bridged? Can someone give me simple terms on how to do this? I am not very car audio savvy haha.

Thanks Everyone!!

-Logan