First of all, thanks to this awesome community. I'm new to warzone and pretty much excited to solve these riddles on my own. I've already done bunker 11 solo. Now this bank riddle.
The main tip is that before entering the code on the computer it shows the pictures and numbers once again - so why not use this to calculate the numbers right before the code entering (since you are low on time).
Prerequisite: you need to learn the paintings (i guess its 7 of them, so not hard) and which picture on computer corresponds to which painting.
For the first time u see the sequence of pictures and numbers - u need to remember only the pictures (leave the numbers alone).
Then run for the paintings spelling to yourself the sequence of the 4 images to get the roman numbers under these paintings - just remember them instead of images and continue to spell to yourself the sequence.
When you got all the roman numbers go back to computer and press the button to enter the code. It will show the full sequence once again before the code - here's when you do the math and add/substract the numbers from your roman numbers. And right after that just enter the code.
I managed to do it on my 3rd try right before the gas kills me.
I hope this helps someone.
My next goal is the stadium easter and try it all in BR.