Answer:
[tex]\dfrac{1}{3} \left (\dfrac{1}{b} - 1 \right )[/tex]
Step-by-step explanation:
[tex]f(x) = \dfrac{1}{3b} - \dfrac{1}{3}[/tex]
1. Find the least common multiple of the denominators
The least common multiple of 3 and 3 is 3.
2. Factor out ⅓.
[tex]\dfrac{1}{3b} - \dfrac{1}{3} = \mathbf{\dfrac{1}{3} \left (\dfrac{1}{b} - 1 \right )}[/tex]