Answer:
[tex] \boxed{ \bold{ \huge {\boxed{ \sf{ - 12 {x}^{2} - 5x - 8}}}}}[/tex]
Step by step explanation
[tex] \sf{ - 9 {x}^{2} + 3x - 8 - (3 {x}^{2} + 8x)}[/tex]
When there is a ( - ) in front of an expression in parentheses, change the sign of each term in the expression
[tex] \dashrightarrow{ \sf{ - 9 {x}^{2} + 3x - 8 - 3 {x}^{2} - 8x}}[/tex]
Collect like terms
[tex] \dashrightarrow{ \sf{ - 9 {x}^{2} - 3 {x}^{2} + 3x - 8x - 8}}[/tex]
[tex] \dashrightarrow{ \sf{ - 12 {x}^{2} - 5x - 8}}[/tex]
Hope I helped!
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