ANSWER
6n
EXPLANATION
The given sequence is
6,12,18,24,...
We can rewrite the terms of the sequence to observe some pattern.
The first term is 6(1)=6
The second term is 6(2)=12
The third term is 6(3)=18
The fourth term is 6(4)=24
Based on this pattern we can generalize that, the nth term of the sequence is 6(n).
Therefore the rule of the sequence is 6n
