The (x, y) coordinates of vertices P, Q and R of a parallelogram PQRS are (-3, -2), (1, -5) and (9, 1), respectively. If the diagonal SQ intersects the x-axis at (a, 0) , then the value of a is
277\dfrac{27}{7}727
103\dfrac{10}{3}310
134\dfrac{13}{4}413
299\dfrac{29}{9}929