actually sorry guys my bad... it should have been " (2001^2 - 1999^2) / (2003^2 - 1997^2) = ? "
i coulnt notice the "a^2 - b^2" fact, thanks for the answer Alan and who tried to help me :)
with the a^2 - b^2 fact i easily found the answer of my question it is 1/3 :)
and im really sory for my mistake, thank you all for helping out :)
