This depends on the country of origin, weight of the letter, priority etc; ask at a post office in your country.
Ask at a post office in USA !
This depend on your country and the type of the mail.
what the price to mail letter to
3 stamps!
About one liberty stamp :)
you need ten stamps actually i don't know
maybe 2 0r 3 stamps
3 stamps.
The number of stamps that you need to send a letter from Australia to London, will depend with the value of one stamp.
2
$1.10 worth of stamps, this may change.
1