Block B moves downward with a constant velocity of 20 mm/s at t=0, block A moving upward with a constant acceleration and its velocity is 30 mm/s. Knowing that at t=3 s slider block C has moved 57 mm to the right, determine (a) the velocity of slider block C at t=0, (b) the acceleration of A and C, (c) the change in position of block A after 5 s.