Simplify the following text for a Grade 6 native English-speaking person.
Original: Saint-Ou Ã `` n-des-Vallons is a commune in the Mayenne department in north-western France .
Simplified: Saint-Ou Ã `` n-des-Vallons is a commune of 174 people ( 1999 ) . It is found in the Pays de la Loire region in the Mayenne department in the northwest of France .