It’s 20 to 9 (Official clock system).

20:40

It’s 20 to 9.

Correct answer

21:20

It’s 20 past 9.

Error: mirror minute hand about the vertical axis

20:00

It’s 8 o’clock.

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

19:40

It’s 20 to 8.

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