Complex sentence: After graduating, he took a job as a business machines salesman but, on his first day, he was invited to play in a seven-card stud game and earned over a month's salary in under three hours.
Split into simpler sentences: After graduating, he took a job as a business machines salesman. His first day on the job, he was invited to play in a seven-card stud game and earned over a month's salary in under three hours.