We cannot exchange items that were bought tax exempt.
We are unable to exchange items that were originally bought exempt from tax.
「免税で購入した商品は返品交換できません」= We cannot exchange items that were bought tax exempt. / We are unable to exchange items that were originally bought exempt from tax.
ボキャブラリー
cannot/unable to = できません
exchange = 返品する
bought = 購入された
tax exempt / exempt from tax = 免税
items = 商品
「レシートを(パスポートの)どのページに貼ればいいですか?」 = Which page shall(can) I put it on? / Which page would you like me to stick the receipt to?
ボキャブラリー
which page = どのページ
shall = しましょうか、~すればいいですか
put it on = 入れる、貼る
would you like me to = してほしい
stick = 貼る
the receipt = レシート