Hi Pawan Ramnani,
I'm going to give you a few 'hints' so that you can try this question again on your own:
1) With graphing questions, it often helps to draw the line(s) described, so that you can physically see the drawing that you'll be working with.
2) After you draw these 3 lines, you'll see a smaller right triangle inside of a larger right triangle. You need to determine the base and height of that smaller right triangle to answer the question.
3) The 'base' of that smaller triangle is the distance between (1,1) and the point on the diagonal line in which Y=1. The same logic can be used to find the height.
GMAT assassins aren't born, they're made,
Rich