Simplify the following text for a Grade 11 native English-speaking person.
Original: Cartesian means relating to the French mathematician and philosopher RenÃ Descartes ( Latin : Cartesius ) , who , among other things , worked to merge algebra and Euclidean geometry .
Simplified: The adjective Cartesian refers to the French mathematician and philosopher RenÃ Descartes ( who used the name Cartesius in Latin ) .