Home Stereo Question

[LittleD]

So my roomate has a boombox setup in our dorm. I got a sub from a friend which has split speaker wire for in and out (2 wires in 2 wires out). The stereo only has 2 black connections and 2 red connections which are being used by the two speakers. Is there anyway i can make this sub work?

Ill throw up pics in a little bit to show what im working with

sub




Stereo