`S=(x/(x^2-36)-(x-6)/(x^2+6x)):(2x-6)/(x^2+6x)+x/(6-x)`
`=(x/((x-6)(x+6))-(x-6)/(x(x+6))):(2x-6)/(x(x+6))-x/(x-6)`
`=((x^2-(x-6)^2)/(x(x-6)(x+6))):((2x-6)(x-6)-x^2(x+6))/(x(x-6)(x+6))`
`=(12x-36)/(x(x-6)(x+6)) : (-x^3-4x^2-18x+36)/(x(x-6)(x+6))`
`=(12x-36)/(x(x-6)(x+6)) . (x(x-6)(x+6))/(-x^3-4x^2-18x+36)`
`=(12x-36)/(-x^3-4x^2-18x+36)`
``
`P=((x+2)/(2-x)+(4x^2)/(x^2-4)-(2-x)/(x+2)):(x^2-3x)/(2x^2-x^3)`
`=((-x-2)(x+2)+4x^2+(x-2)^2)/(x^2-4):(x(x-3))/(x(2x-x^2))`
`=(4x^2-8x)/((x-2)(x+2)):(x-3)/(2x-x^2)`
`=(4x(x-2))/((x-2)(x+2)) . (2x-x^2)/(x-3)`
`=(4x(2x-x^2))/((x+2)(x-3))`
`=(-4x^3+8x^2)/(x^2-x-6)`
