Complex sentence: Brianna enrolled in the new high school, but her living arrangements were unstable and by the end of February she had dropped out of high school, moved in with Stout, and joined a high school equivalency program.
Split into simpler sentences: Brianna enrolled in the new high school, but her living arrangements were unstable. By the end of February she had dropped out of high school, moved in with Stout, and joined a high school equivalency program.