I suggested that an eel restaurant where sales were down put up a sign that says "Dog Days of the Ox", then their sales started booming.
この場合、次のような言い方ができますよ。
ーI suggested that an eel restaurant where sales were down put up a sign that says "Dog Days of the Ox", then their sales started booming.
「売上の下がっていたうなぎ屋さんに”土用の丑の日”の看板を出すように提案したら、大繁盛になった」
an eel restaurant where sales were down で「売上の下がっていたうなぎ屋さん」と言えます。
ご参考まで！
I suggested putting up a "土用の丑の日" sign, and the unagi restaurant, which had low sales, became very successful.
ご質問ありがとうございます。
・「I suggested putting up a "土用の丑の日" sign, and the unagi restaurant, which had low sales, became very successful.」
（意味) 売上げが少なかったうなぎ屋さんに「土用の丑の日（どようのうしのひ）」という看板を出させたところ、大繁盛になった。
・suggested提案した
・successful成功する
参考になれば幸いです。
カナダ 
アメリカ合衆国 
