${x}^{3}-3x+1-\left( {x}^{3}+7-12x \right)$
When there is a $-$ in front of an expression in parentheses, change the sign of each term of the expression and remove the parentheses${x}^{3}-3x+1-{x}^{3}-7+12x$
Since two opposites add up to $0$, remove them from the expression$-3x+1-7+12x$
Collect like terms$9x+1-7$
Calculate the difference$9x-6$