[tex]\bold{\text{Answer:}\quad \dfrac{4(y-4z)}{3y(y+5z)}}[/tex]
Step-by-step explanation:
[tex].\quad \dfrac{12y+8yz}{y^4+9y^3z+20y^2z^2}\cdot \dfrac{y^2-16z^2}{6z+9}\\\\\\=\dfrac{4y(3+2z)}{y^2(y+4z)(y+5z)}\cdot \dfrac{(y-4z)(y+4z)}{3(2z+3)}\\\\\\=\large\boxed{\dfrac{4(y-4z)}{3y(y+5z)}}[/tex]
