(1) 2x + 3y + 7x + 5y
(2) –4a + 8b – 2a – 5b
(3) 5a² + a²
(4) 3x² – 6x + 1– 2x² + 4x
(5) (7a + b) + (–9a + 8b)
(6) (–3x²– 4x) + (5x² – x)
(7) (8x – 6y) – (2x + 4y)
(8) –x² + 9x + 6) – (7x² – 5x + 8)
(9) 2x – 6y – 5 + 3x + 2y – 4
(10) –5x + 8y – 4x – 7y