I recently got some speakers out of a Sharp stereo. I have no idea
what the model of the stereo is, but if it is any help, on the back of
the speaker, it says:
EASJ10P14B3
SPF1759A

I was wondering how I would rig it for use as regular speakers (with
3.5 mm jack) This wouldn't be a problem if the speakers had two cords,
but there are three.

On the negative side of one speaker, there are two cords with black
insulation. One goes to the plug-like thing that probably connected it
to the stereo's main board. The other goes to the negative side on the
other speaker (which accidentally got ripped out but I can probably
solder that back on.) That same speaker has a grey cord on the
positive side that goes to the plug. The other speaker has the
previously mentioned black cord on the negative side and a brownish-
reddish cord on the positive side that goes to the plug.

So my question is, why do regular headphones and speakers have only
two cords, and if I were to modify this for use as a regular speaker,
to plug into my mp3 player or something else, what would I do with the
extra cord, and which one is the extra cord?

Thank you for your help