Answer:
(3b)^4
Explanation:
When a term has an exponent, it means that the term is being multiplied by itself that many times.
For example: 2^3 = 2 x 2 x 2 = 8
So, 3b x 3b x 3b x 3b is the same as saying 3b is multiplied by itself 4 times.
Therefore, it would be (3b)^4