Concept:Polynomial subtraction involves combining like terms after distributing the negative sign.Explanation:We need to subtract the polynomial $(3x^2 + 5x + 3)$ from $(7x^3 + 6x - 9)$.First, write down the expression for subtraction:$(7x^3 + 6x - 9) - (3x^2 + 5x + 3)$Now, distribute the negative sign to each term inside the second parenthesis:$7x^3 + 6x - 9 - 3x^2 - 5x - 3$Next, rearrange the terms in descending order of their powers and group like terms:$7x^3 - 3x^2 + (6x - 5x) + (-9 - 3)$Finally, combine the like terms:$7x^3 - 3x^2 + x - 12$Answer:$7x^3 - 3x^2 + x - 12$