Answer:
If simplifying, then
x^3 -13x^2 -x -49
Explanation:
To do this, I would start off with the left side (use PEMDAS)
Use FOIL (First, Outside, Inside, Last)
x^3 + -9x^2 + 6x + -54 - (4x^2 + 7x - 5)
Bring negatives inside parenthesis
x^3 -9x^2 +6x -54 -4x^2 -7x +5
Combine like-terms
x^3 -13x^2 -x -49