Explanation:
Unfortunately, you haven't given the coordinates of RST so I can't tell you exactly what the new points will be, but I can tell you what process to follow.
To find a new point rotated 90 degrees counterclockwise around the origin, simply apply the rule:
(x,y) ----> (-y,x)
You would apply this rule of switching the x and y coordinates and y becomes the opposite(so if it was a positive coordinate, it becomes negative and if it was negative, it becomes positive), to get your new coordinates.
Hope this helps :)