I saw the following two constructions in Polish:
- Za około dwadzieścia minut
- Po około dwudziestu minutach
And I don't really understand their grammatical rules.
Za takes accusative, 20 and około take genitive, and po takes locative.
However, in the first sentence the number 20 is not declined and minut is declined regularly, but in the second sentence, po declines both the number 20 and the word "minut".
Can someone please explain the construction and what word dictates the declination?