1. I define a coordinate system. The axes are drawn in blue.
2. At the left side of the image you can determine 4 points by their coordinates:
A(0, 2.5), B(0.25, 0.4). Then the straight line through A and B has the equation:
C(0, 0), D(0.2, 1.6). Then the straight line Through C and D has the equation:
3. Calculate the coordinates of the point of intersection. You'll get
4. Do the same at the right side of the image with the points A', B', C', D' and I'.
Calculate the length . I didn't label the points!
5. I've got