The general rule for the nth term of the sequence is 
Explanation:
The sequence is -6b, -3b, 0b, 3b, 6b, .....
To find the nth term of the sequence, we need to find the common difference and the first term of the sequence.
First term of the sequence = -6b
Common difference = 
Using this the nth term of the sequence can be determined.
Since, this is an arithmetic sequence, the general form of AP is given by the formula,

where a denotes the first term of the sequence and d denotes the common difference. Thus,
and 
Substituting the values in the general formula, we get,

Thus, the general rule for the nth term of the sequence is 