20代後半での英語

• in one's late 20s [twenties]〔年齢が〕
  

• 30代後半で:    in one's late 30s [thirties]〔年齢が〕
• 40代後半で:    in one's late 40s [forties]〔年齢が〕
• 50代後半で:    in one's late 50s [fifties]〔年齢が〕

例文

1. she died in her twenties in 1603 .
   1603年に20代後半で死去。
2. women who obtain the jobs do not serve as professional miko for a long time , because most of them retire in their late twenties , having started to work upon the end of compulsory schooling (or more practically , after graduating from high school ).
   女性が本職巫女として奉仕できる年数は短く、義務教育修了後（現実的には高等学校卒業）から勤務し、20代後半で定年を迎える例が多い。