You can put this solution on YOUR website! A DIRECT WAY TO SOLVE THIS PROBLEM IS TO PLOT THE 3 POINTS AND THEN ROTATE THEM 90 DEGREES CLOCKWISE (MOVE THEN TO THE NEXT QUADRANT)
DOING THIS WE GET THE TRANSFER OF POINTS AS FOLLOWS:
1,10=10,-1
5,-10=-10,-5
-10,-8=-10,8