Answer:
[tex] \longrightarrow\tt \: 9 {x}^{3} + 5 {x}^{2} + 11x - 2 {x}^{3} + 9x - 8 {x}^{2} [/tex]
[tex] \longrightarrow \tt \: 9 {x}^{3} - 2 {x}^{3} + 5 {x}^{2} - 8 {x}^{2} + 11x + 9x[/tex]
[tex] \longrightarrow \boxed{\tt \: 7 {x}^{3} - 3 {x}^{2} + 20x}[/tex]
--------- HappY LearninG <3 --------