5) (x^2 - 6x + 9)/(3x - 9) : (3 - x)^2 = (x - 3)^2/3((x-3) * 1 /(3 - x)^2=
= -(3 - x)/ 3 * 1 /(3 - x)^2= - 1/3*(3 - x)
6) (4a + 2b) /(a - 3b) * (6b - 2a) / (b^2 + 4ab + 4a^2) =
= 2(2a + b) / -(3b - a) * 2(3b - a)/(2a + b)^2 = - 4/(2a + b)
7) (3x - 2x^2 - 3y + 2xy) / (x^2 - y^2) =
= [3(x - y) - 2x(x - y)] / (x -y)(x + y) =
= (x - y)(3 - 2x) / (x -y)(x + y) = (3 - 2x) / (x + y)