Three vectors A, B, and C each have a magnitude of 50m and lie in the x-y plane. Their directions relative to the positive x-axis are 30 degrees, 195 degrees, and 315 degrees, respectively. What are (a) the magnitude and (b) the angle of the vector A + B + C, and (c) the magnitude and (d) the angle of A-B+C? What are the (e) magnitude and (f) angle of the fourth vector D such that (A+B) - (C+D) = 0?