Complex sentence: Megadeth is an American thrash metal band from Los Angeles, California, formed in 1983 by guitarist Dave Mustaine and bassist David Ellefson, shortly after Mustaine's dismissal from his previous band Metallica.
Split into simpler sentences: Megadeth is an American thrash metal band from Los Angeles, California. They were formed in 1983 by guitarist Dave Mustaine and bassist David Ellefson, shortly after Mustaine's dismissal from his previous band Metallica.