Question 138376
Expand all the terms inside parens

(-4 + x^2 + 2x^3) – (-6 – x + 3x^3) – (-6y^3 + y^2)

{{{(-4) + x^2 + 2x^3 +6 + x - 3x^3 +6y^3 - y^2}}}

Collect the like terms.

{{{(-4) + x^2 + 2x^3 +6 + x - 3x^3 +6y^3 - y^2}}}
{{{-x^3 + x^2 + x +2 +6y^3 - y^2}}}

That's as far as I can take. Did you get farther than this?