It’s 22 to 9 (Official clock system).

20:38

It’s 22 to 9.

Correct answer

20:39

It’s 21 to 9.

Error: 1 minute later

19:50

It’s 10 to 8.

Error: read minutes starting from hour markings and adding minutes

20:40

It’s 20 to 9.

Error: confuse hour and minute hands