Line L1 passes through the point P(2,−3) and has a slope of 4. Another line L2 is parallel to L1 and passes through the point Q(−1,5).
(i) Find the equations of L1 and L2 in the form y=mx+c.
(ii) Verify that the two lines are parallel.
(iii) Determine the x-coordinates of the points where each line intersects the horizontal line y=1.
(iv) Hence, find the distance between these two intersection points on the line y=1.