Find the volume of the ellipsoid by solving the triple integral after making the transformation and

I'm just a bit confused here because this does not seem like a Jacobian transformation. I know what the triple integral would be in cartesian terms, ie,

But clearly, we don't want to integrate that, so what does it mean by "after making the transformation and "? Do I just simply replace all the x with au and y with bv etc, then what happens to the dz dy and dx?

Thanks heaps!