What's the average amount of money you spend on each meal when you eat out for lunch and supper?
What's the average cost of your meals when you eat lunch and supper at a restaurant?
この場合、次のような言い方ができますよ。
ーWhat's the average amount of money you spend on each meal when you eat out for lunch and supper?
「昼食と夕食を外で食べる時、それぞれの食事にかける平均の値段はいくらですか？」
What's the average amount of money ...? を使って平均の値段を聞くことができます。
ーWhat's the average cost of your meals when you eat lunch and supper at a restaurant?
「レストランで昼食や夕食を食べる時、平均の食事代はいくらですか？」
What's the average cost of ...? を使って平均の値段を聞くこともできます。
ご参考まで！
The average cost for one meal when dining out for both lunch and dinner.
What's the average cost for one meal when dining out for both lunch and dinner?
ご質問ありがとうございます。
・「The average cost for one meal when dining out for both lunch and dinner.」
（意味)外食時の昼食と夕食それぞれの1回の[平均](https://eikaiwa.dmm.com/uknow/questions/38711/)の食費
・「What's the average cost for one meal when dining out for both lunch and dinner?」
（意味) 外食時の昼食と夕食それぞれの1回の平均の食費はいくらですか？
<例文>What's the average cost for one meal when dining out for both lunch and dinner?// I have a lot of allergies so I don't really eat out.
<訳> 外食時の昼食と夕食それぞれの1回の平均の食費はいくらですか？//私いろんなアレルギーがあるので普段は外食しません。
参考になれば幸いです。
カナダ 
アメリカ合衆国 
