Simplify the following text for a Grade 7 native English-speaking person.
Original: Gian Gastone de ' Medici ( Giovanni Battista Gastone ; 24 May 1671 -- 9 July 1737 ) was the seventh and last Medicean Grand Duke of Tuscany .
Simplified: Gian Gastone de ' Medici ( 24 May 1671 â `` 9 July 1737 ) was the last Medici Grand Duke of Tuscany .