The image would coincide with the pre-image during the rotation. Therefore, the octagon would coincide a total of 8 times as it rotates 360 degrees about its center.
Just multiply straight across. (Left to right.)
Multiply both numbers on the top then both on the bottom. Then just simplify.
An example is 1/2 x 3/4 = 3/6 then 1/2
X=-2x-5 x=3
x=-2(3)-5
x=-6-5
x= -11