Perform the indicated operations. Write the resulting polynomial in standard form and indicate its degree.
a) (-6x³ + 7x² - 9x + 3) + (14x³ + 3x² - 11x - 7)
Polynomial: 8x³ + 10x² - 20x - 4, Degree: 3
b) (13x⁴ - 8x³ + 2x²) - (5x⁴ - 3x³ + 2x² - 6)
Polynomial: 8x⁴ - 5x³ + 4x² + 6, Degree: 4