Automatically adjust cameras FOV to maintain a perfect 360 coverage with multiple cameras

Hi,

I'm currently developing a system that instantiates a user-defined amount of cameras, which we'll call X. I've already managed to write it so that Unity automatically calculates the angle apart that they all need to be so that they are looking in a circle between them, but I need to adjust their field of view on a per camera basis so that if X increases, the FOV per camera decreases to maintain the same overall FOV for if 3 cameras were available and in reverse.

If anybody could help, that would be great. Thanks in advance!