It’s 21 to 9 (Official clock system).

08:39

It’s 21 to 9.

Correct answer

08:40

It’s 20 to 9.

Error: 1 minute later

07:53

It’s 7 to 8.

Error: read minutes starting from hour markings and adding minutes

07:39

It’s 21 to 8.

Error: confuse hour and minute hands and read as nearest hour