problem with preposition

[Unregistered]

Hello Teachers.

Could you please tell me which prepositioin in correct in #1 and which of #2 is correct?

1.Open your book on/at page 30.
2.
a) What page should I open my book on?
b) Which page should I open my book on?

Thanks in advance

[Alc112]

2.
a) What page should I open my book on?
b) Which page should I open my book on?

Thanks in advance

ABout #2:
As far as i know, you can use tthe two forms you suggest. But is more common to say What page.

Ho I'm correct and not Wrong

[Tdol]

In British English, you say 'open your book at page 37', but you would say that 'the article is on page 37'.