Simplify the following text for a Grade 7 native English-speaking person.
Original: Upon Horton 's death in 1974 , Joyce bought out the Horton family 's shares for $ 1 million and took over as sole owner of the existing chain of forty stores .
Simplified: After Horton 's death in 1974 , Joyce bought the company from the Horton family and took over as the only owner of the now forty stores .