Answer:
[tex]\left(3x^3+2x-3\right)-\left(4x^3-x^2+x\right)=-x^3+x^2+x-3\\\mathrm{Remove\:parentheses}:\quad \left(a\right)=a\\3x^3+2x-3-\left(4x^3-x^2+x\right)\\3x^3+2x-3-4x^3+x^2-x\\-x^3+x^2+x-3[/tex]
I hope this is good enough: