Complex sentence: Mozart had just returned to the city after 18 months of fruitless job hunting in Paris and Mannheim, and his father Leopold promptly got him a job as court organist and composer at Salzburg Cathedral.
Split into simpler sentences: Mozart had just returned to the city after 18 months of fruitless job hunting in Paris and Mannheim. His father Leopold promptly got him a job as court organist and composer at Salzburg Cathedral.