Answer:
[tex]\frac{1}{3}[b-1][/tex]
Step-by-step explanation:
we have
[tex]\frac{1}{3}b-\frac{1}{3}[/tex]
Factor the coefficient [tex]\frac{1}{3}[/tex] of both terms
[tex]\frac{1}{3}b-\frac{1}{3}=\frac{1}{3}[b-1][/tex]