Complex sentence: He has been offered a substantial sum of money to have the house torn down and the site developed into condominiums; but he is intrigued by the paranormal history of the house, and has agreed to allow one more investigation of the mansion.
Split into simpler sentences: He has been offered a substantial sum of money to have the house torn down and the site developed into condominiums. But he is intrigued by the paranormal history of the house, and has agreed to allow one more investigation of the mansion.