Simplify the following text for a Grade 11 native English-speaking person.
Original: The MureÅ ( Romanian MureÅ ; Hungarian Maros ; Latin : Marisus , Croatian : MoriÅ , German : Mieresch , Marosch or Muresch , Serbian : Ð Ð 3\/4 Ñ Ð Ñ , Ð Ñ Ñ Ð Ñ ) is an approximately 761 km ( 473 mi ) long river in Eastern Europe .
Simplified: The MureÅ ( Romanian ) ( , Latin : Marisus , Croatian : MoriÅ , German : Mieresch , Marosch or Muresch , Serbian : Ð Ð 3\/4 Ñ Ð Ñ , Ð Ñ Ñ Ð Ñ ) is a 761 km ( 473 mi ) long river in Eastern Europe .