Question 635304
={{{((y^2-9)/(y^2-3y))(y/(y^2+9y+18))}}} 
={{{((y^2-3^2)/y(y-3))(y/(y^2+6y+3y+18))}}} 
={{{((y-3)(y+3)/y(y-3))(y/(y(y+6)+3(y+6)))}}} 
={{{(cross((y-3))(y+3)/y(cross((y-3))))(y/(y+3)(y+6))}}} 
={{{(cross((y+3))/cross(y))(cross(y)/cross((y+3))(y+6))}}}
={{{1/(y+6)}}}