Let's simplify the expression step by step:

cos(180-x) = -cos(x)sin(180-x) = sin(x)cos(90-x) = sin(x)sin(90-x) = cos(x)

Now we can substitute these values into the expression:

(-cos(x))(sin(x)) - (sin(x))(cos(x))

= -cos(x)sin(x) - sin(x)cos(x)

= -2cos(x)sin(x)

Therefore, Cos(180-x)sin(180-x)-cos(90-x)sin(90-x) simplifies to -2cos(x)sin(x).