Draw a careful diagram showing these two points on a squared grid. Draw the line segment that joins them and extend it in each direction by of its own length. So at the left-hand end that's to the left and units up; at the right-hand end that's units to the right and units down. If you draw this with care, you should see immediately what the coordinates are.
The left-hand end point has -coordinate ; and -coordinate .
The right-hand end has -coordinate ; and -coordinate .