Answer:
it can be used to determine the next high by simply dividing the previous number by 1.5
27/1.5=18 (1st to 2nd)
18/1.5=12 (2nd to 3rd)
12/1.5=8 (3rd to 4th)
Step-by-step explanation:
you need to find the similarity in them first check if they add or subtract the same numbers.
  -9    -6
27 Â Â 18 Â Â Â 12
so no. Which means it has to be a factor or a division.
27/1.5=18
18/1.5=12
12/1.5=8
and so it continue