The clothes I bought were an additional 50% off the sale price.
The clothes I purchased were half price off the already reduced price.
ーThe clothes I bought were an additional 50% off the sale price.
「買った服はセール価格から追加の50％オフだった」
additional で「追加の」
sale price で「セール価格」
ーThe clothes I purchased were half price off the already reduced price.
「買った服は、すでに割り引かれた価格から半額だった」
to purchase で「購入する」
half price で「半額」
reduced price で「割引価格」
ご参考まで！
The discounted clothes were marked down to half price.
The discounted clothes were marked down to half price.
The clothes that were already on sale got even cheaper — they’re now half off.
「値引きされていた服がさらに半額になりました」は、英語で **“The discounted clothes were marked down to half price.”** や **“The clothes that were already on sale got even cheaper — they’re now half off.”** のように言うことができます。
カナダ 
アメリカ合衆国 
