Block B moves downward with a constant velocity of 20 mm/s. At t=0, block A is moving upward with a constant acceleration, and its velocity is 30 mm/s. Knowing that at t= 3s slider block C has moved 57 mm to the right, Determine 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 5s.