CPM Homework Help : INT3 Problem 12-30

What is the sum of each infinite series (if possible)?

$6+3+\frac{3}{2}+...$
Hint (a):
How is this sequence progressing? How will that help you to find the sum?
Answer (a):
$12$

$\displaystyle\sum _ { k = 1 } ^ { \infty } ( \frac { 1 } { 3 } ) ^ { k }$
Hint (b):
What are the first term and multiplier of the sequence?