Question 886761
I think it can be done more easier way as follows:
Let, the capacity of bucket is x L and
     the capacity of tank is y L.
Then, y/x=12.....(1)
now the capacity of smaller bucket should be 2x/3.
Therefore, the number of buckets needed are y/(2x/3)=3y/2x
from eqn (1).......we get 3*12/2=18 buckets