A straight line L1 has a gradient ˉ½ and passes through point P (−1, 3). Another line L2 passes through the points Q (1, -3) and R (4, 5). Find.

- The equation of L1.
- The gradient of L2.
- The equation of L2.
- The equation of a line passing through a point S (0, 5) and is perpendicular to L2.
- The equation of a line through R parallel to L1.