`#Kenshiro`
`⇒ M = ( (3+x)/(x-3) - 18/(9-x^2) + (x-3)/(x+3) ) : ( 1 - (x+1)/(x+3) )`
`⇒ M = ( ((x+3)^2)/(x^2-9) - 18/(9-x^2) + ((x-3)^2)/(x^2-9) ) : 2/(x+3)`
`⇒ M = ((x^2+6x+9-18+x^2-6x+9)/(x^2-9) ) xx ((x^2-9)/(2.(x-3)))`
`⇒ M = (2x^2)/(x^2-9) xx (x^2-9)/(2.(x-3))`
`⇒ M = (x^2)/(x-3)`