I need help with Geometry

 180 degrees

Imagine you had a long and flat rectangle. If we spin it around the center, we can rotate it 180 degrees so it lines up with its original image. The before and after is the same. We say it has rotational symmetry, and the angle of rotation is 180 degrees. This is the smallest rotational angle possible for rectangles that aren't squares.

combine all like terms then its just a 2 step equation