That would be 1/2 divided by 3
Its A
0.735 expressed as a fraction is 3/8
Rotation 90° translates (x, y) to (-y, x). Thus (3, 2) gets translated to (-2, 3). Your green box gets filled with -2.
Slope = difference in y / difference in x
slope = 5 - 0 / 4 - 10
slope = 5 / -6
slope = -.83333