You can put this solution on YOUR website! Get some graph paper.
Plot A and M, and draw a line from A through M
and indefinitely beyond M.
From A draw a vertical line segment (in red) down to the same level as M,
then from the endpoint of that line segment draw a horizontal line segment
left over to M. Count the number of units you went down, which was 5 units
down. Now count the number of units you went left to get to M, which was
4 units left.
Now do the same thing at M. Draw a line 5 units down, then 4 units left,
and you'll end up at B.
So mark the point B where you ended up, at (1,-8). Erase the rest of
the green line.
Answer: (1,-8)
Edwin