Joint Variation, in Depth

The volume of a pyramid, $v$, varies jointly with the area of it's base, $b$, and the height, $h$. If the volume of a pyramid is $15\text{ units}^3$ when the base is $5 \text{ units}^2$ and the height is $9 \text{ units}$, what is the volume of a pyramid with base of $6 \text{ units}^2$ and height of $8 \text{ units}$?