Add:
(i) 3x2y, -5x2y, -x2y
(ii) a + b – 3, b + 2a – 1
(i) 3x2y, -5x2y, -x2y
= 3x2y + (-5x2y) + (-x2y)
= 3x2y – 5x2y – x2y
= (3 – 5 – 1 )x2y
= -3x2y
(ii) a + b – 3, b + 2a – 1
= (a + b – 3) + (b + 2a – 1)
= a + b – 3 + b + 2a – 1
= a + 2a + b + b – 3 – 1
= 3a + 2b – 4