Answer:
P(x) + q(x)
= (3x² + 5x² + 4x - 7) + (6x³ + 2x² - 9x - 5)
= 3x² + 5x² + 4x - 7 + 6x³ + 2x² - 9x - 5
= 6x³ + 10x² - 5x - 12
P(x) - q(x)
= (3x² + 5x² + 4x - 7) - (6x³ + 2x² - 9x - 5)
= 3x² + 5x² + 4x - 7 - 6x³ - 2x² + 9x + 5
= -6x³ + 6x² + 13x - 2
