It’s 28 to 9 (Official clock system).

20:32

It’s 28 to 9.

Correct answer

20:33

It’s 27 to 9.

Error: 1 minute later

19:52

It’s 8 to 8.

Error: read minutes starting from hour markings and adding minutes

18:40

It’s 20 to 7.

Error: confuse hour and minute hands