Answer:
where (a,b) represents the coordinates for the pre-image and (-b,a) represents the coordinates for image.
Explanation:
After rotating a figure 270° counterclockwise, then the x-coordinate interchanges with negative value of y-coordinate and y-coordinate interchanges with the value of -x coordinate.
The rule for rotating the figure 270° counterclockwise is given by :-

where (a,b) represents the coordinates for the pre-image and (-b,a) represents the coordinates for image.