Vector AB with origin at point A (-3; -9) has coordinates (8; 3) find the sum of coordinates of point B.

Since the vector AB has coordinates (8; 3), and the coordinates of point A (-3; -9), then the coordinates of point B can be obtained from the formula for calculating the coordinates of the vector, according to the coordinates of its beginning and end.
Let’s denote the coordinates of the point B (x; y), then 8 = x – (-3); 3 = y – (-9);
Hence: 8 = x + 3, x = 8 – 3 = 5;
3 = y + 9, y = -6;
This means that the coordinates of point B are (5; -6), and the sum of the coordinates of point B is 5 + (-6) = 5 – 6 = -1.
Answer: the sum of the coordinates of point B is -1.