Notice that the line cuts right across the corners of the grid 
squares of the graph paper.

The upper (blue) part of the line [from (6,0) to (9,3) ]

cuts through the corners of 3 grid squares. 

and the lower (red) part of the line [from (2,-4) to (6,0) 

cuts through the corners of 4 grid squares.

So the blue part of the line is ¾ as long as the red part.

So one possible answer is (6,0).

But the answer could also be like the graph below

and the answer could be (5,-1).



So there are two possible answers (6,0), and (5,-1), depending on
whether the upper (blue) part of the line is ¾ as long as the 
lower (red) part of the line, or vice-versa.

Edwin