21a - 16b + 18c - 6a - 7b - 4c

Answer 1

21 a - 16 b + 18 c - 6 a - 7 b - 4 c =

21 a - 6 a - 16 b - 7 b + 18 c - 4 c =

15 a - 23 b + 14 c