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Explanation:
The rule for a 90 degree counterclockwise rotation is
[tex](x,y) \to (-y,x)[/tex]
This rule only works if the center of rotation is the origin.
If we apply that rule to point N, then we have
[tex](x,y) \to (-y,x)\\\\(3,-1) \to (-(-1),3)\\\\(3,-1) \to (1,3)[/tex]
Therefore, point N' is located at (1,3)
Check out the diagram below.
