What is 12(3-1/6t) because i'm really lost

Mary beth used the mapping rule to find the coordinates of a point that had been rotated 90° counterclockwise around the origin. examine the steps to determine whether she made an error. m (3, –6) is rotated 90° counterclockwise. (x, y) → (–y, x) 1. switch the x- and y-coordinates: (6, –3) 2. multiply the new x-coordinate by –1: (6(–1), –3) 3. simplify: (–6, –3) .

Which coefficient matrix represents a system of linear equations that has a unique solution ? options in photo*

How can (square root of 25) ^2 be rewritten?