I would need to see the drop down, but I think it's perpendicular and touching.
We know that
[<span>inside volume of the tank]=[40-2]*[50-2]*[20-1]------> (the top is open)
</span>[inside volume of the tank]=[38]*[48]*[19]----> 34656 cm³
the answer is
the inside volume of the tank is 34656 cm³
Kilowatts of power are used each hour
104/13=8