Complex sentence: Greene worked many jobs to put himself through college at Johns Hopkins, where he graduated with a B.A. in economics and sociology in three years, and later Harvard Business School, where he earned his Master of Business Administration (MBA) degree in 1977.
Split into simpler sentences: Greene worked many jobs to put himself through college at Johns Hopkins University, graduating in three years with a B.A. in economics and sociology. Later he attended Harvard Business School, where he earned his Master of Business Administration (MBA) degree in 1977.