The formula to find density is Mass/Volume
We have
Density =

Volume =

Hence
Mass = 7.8×10504 = 81931.2 gram
Answer: 4712.39 centimeters
Step-by-step explanation: Using the volume of a cylinder calculator, I got the answer of 4712.3889803847 centimeters, but rounded it to the nearest hundreth. Hope this helps!
Here is the link to the graph. You can scale it and tweak it.
https://www.desmos.com/calculator/mawkflj9ws
Hope this helped!
I don't get how it would be a system of equations.
The volume is 4.19ft³ Hope it helps <3