Which algebraic rule describes the 270° counter-clockwise rotation about the origin?

Let's say the point is (x,y) and it lies in 1st quadrant with both x and y as positive , Now let's say that the point is rotated by 270 degrees counter clockwiseIt means The point will shift to the 4th quadrant , and we know that in 4th quadrant , the x is positive and y is negative , Also , as it is rotated by 270 degrees , the x and y values will interchange
SO there are two steps 1) Change the sign of x2) Interchange the x and y values , i.e swap , x with y and y with x