Math help please? Not sure I am getting this. ?

(y^2 - 6y + 9)/-(y^2 - 4) ÷ (y^2 - 9)/(y^2 - 8y + 12)
= (y^2 - 3y - 3y + 9)/-(y^2 + 2y - 2y - 4) * (y^2 - 2y - 6y + 12)/(y^2 + 3y - 3y - 9)
= (y - 3)(y - 3)/-(y + 2)(y - 2) * (y - 2)(y - 6)/(y + 3)(y - 3) (cancel out y - 3 , y - 2)
= (y - 3)/-(y + 2) * (y - 6)/(y + 3)
= (y - 3)(y - 6)/-(y + 2)(y + 3)

your question is not clear

Factorise all terms

and get the answer

for eg factor of y^2-6y+9 = (y - 3)(y - 3)
y^2 - 9 = (y-3)3(y+3)
y^2 -4 = (y+2)(y-2)
y^2 - 8y +12 = (y-2)(y-6)

I cannot understand. there is a lot of decoration there. The main problem cannot be understood! Well use the following if you can!
y^-6y+9 = (y-3)^2
y^2 -9= (y-3)(y+3)
y^2 - 4 = (y-2)(y+2),
y^ - 8y +12 = (y-6)(y-2)
(a/b)/(c/d) = ad/bc.