回答
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Please take this proposal back to your company and consider it. Please respond next week.
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You can take this proposal back with you and give it some more thought. Get back to us with your decision sometime next week.
上記の一番目は直訳。礼儀正しくて、ちょっと硬いです。2番目はもっとアメリカっぽい言い方です。