Why sometimes writing numbers as numbers (20) is ok but not here?
Because by writing numbers you don't really learn new language content in a lesson about numbers.
Or if by any chance in other than the "numbers" lesson, you just learn less.
Not дво́ра, but двора́.
I can't get it to accept my pronunciation because it keeps marking двадцать метров and пятнадцать wrong. Pretty sure I'm not mispronouncing them (not worse than the rest of the phrase for sure). Am I the only one?
I have the same issue.
A yard measured in metres...! Actually, the length of an inch is officially standardised as 25.4 millimetres :)
The answer was already given