"For a limited time we are offering 3 extra pieces of fried chicken."
"For a limited time only, we are increasing the quantity of fried chicken by 3 pieces."
- "For a limited time we are offering 3 extra pieces of fried chicken."
"for a limited time" 「[期間限定](https://eikaiwa.dmm.com/uknow/questions/28127/)で」
"we are offering" 「を[提供](https://eikaiwa.dmm.com/uknow/questions/34405/)しています」
"3 extra pieces" 「3個増量」
"fried chicken" 「[唐揚げ](https://eikaiwa.dmm.com/uknow/questions/46460/)」
- "For a limited time only, we are increasing the quantity of fried chicken by 3 pieces."
"for a limited time only" 「期間限定で」
"we are increasing the quantity of fried chicken by 3 pieces" 「唐揚げ3個増量中です」
"increasing the quantity" 「量を増やす」
「いかがですか」は英語で言わなくていいです。このまま言えばお客さんが答えます。でも、「いかがですか」と言う意味の言葉を言いたかったらこう言えます。
"would you like some?" 文書の後に付けます。
"If you are interested ~" 文書の前に付けます。
"If you are interested, for a limited time we are offering 3 extra pieces of fried chicken."
"For a limited time only, we are increasing the quantity of fried chicken by 3 pieces. Would you like some?"
We're giving an extra three pieces of deep-fried chicken with every order for a limited time.
この場合、次のような言い方ができると思います。
ーWe're giving an extra three pieces of deep-fried chicken with every order for a limited time. Would you like to try an order?
「[期間限定](https://eikaiwa.dmm.com/uknow/questions/28127/)で[唐揚げ](https://eikaiwa.dmm.com/uknow/questions/46460/)３個余分につけています。いかがですか？」
to give an extra three pieces of ... で「…３個を余分にあげる」
ーWe're offering three extra pieces of Karaage for a short time only.
「[短期間](https://eikaiwa.dmm.com/uknow/questions/71314/)の間、唐揚げを３つ余分につけています」
to offer three extra pieces of ... で「…を３個余分に差し上げる」
ご参考まで！
オーストラリア 
カナダ 
