Can anyone help with a fuel enquiry?

We paid for gold hire with Alamo. We had to exchange our vehicle. The old vehicle had 1/4 tank remaining when we gave it back . The new vehicle came with a full tank.

When we return the vehicle at the end of the hire period do we return it with 3/4 tank or do we pay Alamo for the extra 3/4 tank we will have had the benefit of.

Thanks Nadine