The document contains expressions involving variables and numbers that need to be combined and simplified using the rules of algebra. It provides several multi-term expressions and asks the reader to reduce them by combining like terms.

1. Reduce:
 5a + 12b – c + 3a – 8b – 4c
 22a – 13ab + 50ab + 17a
 4a + 3b – 2c – b – c + 2c – a
 50x – 11y – 19 + 20x – 10 – 7y
 – 16m + 80n + 15 – 2m – 3n – 6m – 11
 – 18x + 49y – 40z + 8y + 30x + x – 15y

2. Reduce:
 5a + 4b + 8c – (a + 2b + 2c)
 6(x + y) + 3(x + y) – 9(x – y)
 3(2x – 1) + 5(3x – 1) + 8(4x – 1) + 9
 5x – [2x + y – (4x + y)]
 8x + 2 – {(–2x + 3) + (–3x + 5)}
 5x + 6y + [7x – 9y + z] - {x + y – z}
 3(a + b) – 2(– a – b) + (–b + a) – (3a – b)

3. Sean:
A = –7x4 + x3 – 2x – 7
B = 4x3 + 6x2 – x + 1
C = –2x3 + x2 + 8x – 3
Calcula:
1) A – B 2) B – C
3) (A + B) – C 4) (A – B) – (B – C)