If these are separated like:
(6+8)*x, 4x+4+21, 4(2x+3), 6x+8x, 16(x+y+z), 8x+4+31, 4(x+2), and 6x+6y+6z...
Then it will be (6+8)*x with 6x+8x, 4x+4+21 with 8x+4+31, 4(2x+3) with 4(x+2), and 16(x+y+z) with 6x+6y+6z. Due to like terms, it only makes the most amount of sense.
What's bolded is your answer.