Complex sentence: The girl was between fourteen and seventeen, although she may have been as young as twelve and as old as twenty-five and had possibly been hitchhiking around the southern United States, in Oklahoma, Texas, Louisiana and Nevada.
Split into simpler sentences: The girl was between fourteen and seventeen, although she may have been as young as twelve and as old as twenty-five. She had possibly been hitchhiking around the southern United States, in Oklahoma, Texas, Louisiana and Nevada.