Complex sentence: The Yount-Lee Oil Company was founded in 1915 and was the successor company to the Yount Oil Company which had been formed two years earlier by Frank Yount when he took on two partners, brothers T.P. Lee and William H. Lee.
Split into simpler sentences: The Yount-Lee Oil Company was founded in 1915 and was the successor company to the Yount Oil Company which had been formed two years earlier by Frank Yount. Yount took on two partners, brothers T.P. Lee and William H. Lee.