Answer:
[tex]\huge\boxed{b=\dfrac{3V}{h}}[/tex]
Step-by-step explanation:
[tex]V=\dfrac{1}{3}bh\qquad\text{multiply both sides by 3}\\\\3V=3\!\!\!\!\diagup^1\cdot\dfrac{1}{3\!\!\!\!\diagup_1}bh\\\\3V=bh\qquad\text{divide both sides by}\ h\neq0\\\\\dfrac{3V}{h}=\dfrac{bh}{h}\\\\\dfrac{3V}{h}=b\to \boxed{b=\dfrac{3V}{h}}[/tex]
