Find the value of two numbers if their sum is 12 and their difference is 4 . (word problems/ writing system of equations)

How many days was the temperature above 90 degrees?

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) .

We just started the introduction into circles and i have no idea how to do this.