Resposta :
Letra C.
[tex]20 - (3x + 2) \: . \: (3x - 5) \\ \\ 20 - (9x {}^{2} - 15x + 6x - 10) \\ \\ 20 - (9x {}^{2} - 9x - 10) \\ \\ 20 - 9x {}^{2} + 9x + 10 \\ \\ 30 - 9x {}^{2} + 9x \\ \\ \boxed{\boxed{\boxed{ - 9x {}^{2} + 9x + 30 }}} \\ [/tex]
Letra C.
[tex]20 - (3x + 2) \: . \: (3x - 5) \\ \\ 20 - (9x {}^{2} - 15x + 6x - 10) \\ \\ 20 - (9x {}^{2} - 9x - 10) \\ \\ 20 - 9x {}^{2} + 9x + 10 \\ \\ 30 - 9x {}^{2} + 9x \\ \\ \boxed{\boxed{\boxed{ - 9x {}^{2} + 9x + 30 }}} \\ [/tex]