Complex sentence: He left school at 15 and took a series of low-paying jobs, began breaking into houses in 1976, and was sent to borstal for a few months in 1977.
Split into simpler sentences: He left school at 15 and took a series of low-paying jobs, before starting to get into trouble with the law. He began breaking into houses in 1976, and was sent to borstal for a few months in 1977.