Please help me understand this

The problem reads- you are simplifying the following: (3x^3+6x^2-x-4)-(4x^3+8x^2+5x-2)
Fill in the blanks with the correct sign.
3x^3_ 6x^2_ x_ 4_ 4x^3_ 8x^2_ 5x_ 2

To simplify the expression, we need to combine like terms. Let's rewrite the expression by grouping like terms together:

(3x^3 + 6x^2 - x - 4) - (4x^3 + 8x^2 + 5x - 2)

Arrange like terms together:

(3x^3 - 4x^3) + (6x^2 - 8x^2) + (-x - 5x) + (-4 - 2)

Now simplify each group:

-1x^3 - 2x^2 - 6x - 6

Therefore, the blanks should be filled with the following signs:

3x^3 - 6x^2 - x - 4 - 4x^3 + 8x^2 + 5x + 2