Songs that were popular when people currently in their 70s~80s were young.
「今の70代〜80代の方が若い頃に流行っていた曲」
- Songs that were popular when people currently in their 70s~80s were young.
「今の70代〜80代の方が若い頃に流行っていた、昔の曲が好きです」
- I like songs that were popular when people currently in their 70s~80s were young.
- I like old songs that were popular when people in their 70s and 80s were young.
I like songs that were popular with people in their 70's and 80's when they were young.
この場合、次のような言い方ができます。
ーI like songs that were popular with people in their 70's and 80's when they were young.
「70代、80代の人が若かった時に流行っていた曲が好きです」
songs that were popular で「人気だった曲・歌」
people in their 70's and 80's で「70代、80代の人たち」
ご参考まで！
アメリカ合衆国 
カナダ 
