one part...nine parts

今日は単語の話題ではなく、割合を示す表現ですが、なるほどこう言う表現法もあるのだと知ったReader's Digest 5月号の記事 'Clean the Things You Never Do' です。

If not, mix one part white vinegar and nine parts water (or two parts lemon juice and eight parts water), fill the reservoir with the mixture, and run a drip cycle.
...

Mix equal parts baking soda and hydrogen peroxide with a splash of degreasing dish soap.

"part" と "parts" の使い分けも注意しないとね。