Answer:
(a) The sum of the previous term and 9
(b) 36, 45, 54
Explanation:
Given
Sequence: Arithmetic Progression

Solving (a): Describe the relationship in each term
First, we calculate the common difference (d)
In arithmetic progression:

Take n as 2


Where



The relationship is: The sum of the previous term and 9
Solving (b): The next three terms
As said in (a) each term is derived from a sum of 9 and the previous term
So, we have:



Hence, the next three terms are: 36, 45 and 54