Simplify: 5x2(x+3)−x35x^2(x + 3) - x^35x2(x+3)−x3.
4x3+15x24x^3 + 15x^24x3+15x2
4x3+15x34x^3 + 15x^34x3+15x3
5x3+15x25x^3 + 15x^25x3+15x2
6x3+15x26x^3 + 15x^26x3+15x2