What is the Greatest common monomial factor of the following

1.)y^3 + 9y

2.)4a^4 b^3 - 20a^3 b^6 + 16a^2 b^9

3.)25x^2 y^3 - 100x^3 y^2

4.)9 - 6x + 27y

5.)12t^5 - 36t^3 + 16t

(Free follow to who ever answers correctly)​