Answer: b ≤ -18
Step-by-step explanation:
Isolate the variable by multiplying both sides by -3. Remember that when you multiply or divide by a negativem the symbol flips.
[tex]\dfrac{b}{-3}\geq6\\\\\\\dfrac{b}{-3}(-3)\geq6(-3)\\\\\\\large\boxed{b\leq-18}[/tex]