not look a day over (age in years)

not look a day over 40　= you look younger than 40. 40には見えませんね。 3:34 you look fantastic. you don't look a day over 75. きれいだよ。とても75には見えないね。

100 Years of Beauty: Aging | Cut Has A Field Day

2:01 30 years later, George doesn't look a day over prehistoric. それから30年、カメのジョージはとても古代生物には見えない。

10-year-old girl keeps same pet tortoise 56 years

2:54 I am now 52, and Michelle says that I don't look a day over 51.私は52歳だが、妻は51くらいにしか見えないと言うんだ。

President Obama Speaks on Restoring Security to Homeownership

14:35 you don't look a day over 50. あなたは50歳にも見えませんよ。

Long Term Raw Vegan Has a Stroke: Why a Raw Diet May Not be Healthy

参考リンク
http://bridge-english.blogspot.com/2020/11/havent-aged-day.html  haven't aged a day　全然歳をとっていない

練習問題解答
b-1703 I look a day over
b-4936 you don't look one day over
b-5708 feel a day over a hundred and twenty