It’s 17 past 8 (Official clock system).

20:17

It’s 17 past 8.

Correct answer

20:18

It’s 18 past 8.

Error: 1 minute later

20:05

It’s 5 past 8.

Error: read minutes starting from hour markings and adding minutes

15:40

It’s 20 to 4.

Error: confuse hour and minute hands