How do you end a slideshow when the Audio track is longer than the Slides?

I want to end a slideshow at the end of the slides eg at 5:45, then export as a Quicktime movie. The 1 audio track I am using as background sound is a duration of 19:00, I have inserted an audio marker at the end of the slides however the slideshow continues to run black after the last slide. Is it possible to cut the audio track? How do I get the slideshow to end at the last slide?

I’d use Garageband or Audacity to create a cut down version of the audio track that fades out at 5.45.

I’m using FM3.8.8. When my sound track exceeds the length of the show, I grab the excessive end of that bar and drag it back to the end of the show. It’s an abrupt cut off, not a gradual fade, though.