???? i did vector OA + vector AD = OD but its still wrong

For the points A(2, 5, -9), B(8, -6, -9) and C(0, 4, 3) you are given that -8 AB = -11 AC = -1 and BC = 10 12 12 Find the position vector OD of the point D such that the quadrilateral ABDC (named in cyclic order) is a parallelogram. (Check the order carefully!) Enter your answer for OD in the box below using Maple notation. For example, for the vector 2 enter . Note that your answers should be exact and not decimal approximations. OD = X