Question

Which number comes next in the series: 21..18..15..12..?*

Answer 1

Answer:

9 is the answer dude MAKE ME BRAINLIST

Answer 2

Answer:

The answer is 9

Step-by-step explanation:

21-3=18

18-3=15

15-3=12

12-3=9

Please mark my answer as the Brainliest.