Help with (likely) fairly simple formula (Algebra?)

First off, I want to express that I'm frustrated with myself/the situation as this is the sort of thing I'd typically be able to work through and figure out myself - however, I'm a few weeks into concussion recovery and a big focus for me is learning to actually ask for help when I need it rather than pushing myself too far, so here I am (and already feel my brain progressively scrambling as I write this out).

Now that we're past that, I have an excel document I am creating whose objective is to house a repository of commercial monitor (TV) and multi-monitor mount dimensional statistics, with the goal of being able to select one of each and have it spit out the minimum (without the mount being visible) and maximum number of the selected TVs that will fit on said mount. If you're having any trouble visualizing what I'm talking about think about a typical monitor wall mount where it's basically a rail on the wall, only wider such that you can hang multiple TVs side by side

So for an example with a visual illustration and I'll use millimeters here to make the math easier, you have a mount with a usable mounting surface of 1000mm, and a TV with a width of 400mm (portrait if that seemed unrealistic) with 200mm VESA mounting pattern. For the sake of simplification I'll assume the VESA mount is centered on the TV centerline, but if anyone helping can incorporate distance from the vesa pattern and left/right into the formula that would be ideal (But 100% optional).

So the minimum (again, minimum number of monitors to cover up the entire mounting surface) is pretty simple - mount width (1000) / monitor width (400) = 2.5, round up to get to 3.

Maximum is where I'm getting more than a bit stuck and having problems translating my usual manual work into a flexible formula. So in this specific example, I'd take the following steps to get to my answer after determining the minimum monitors. In this exact example the minimum and maximum are the same, but there's cases where they're different.

Distance from the interior most VESA mount point to exterior most - Monitor width / 2 - VESA width / 2 + VESA width = 400/2 - 200 / 2 + 100 = 300

1000mm mount - 300mm from the outside-left monitor - 400mm from the interior monitor leaves 300mm for the outside - right monitor or just barely enough.

Problem one is that just tells me whether x number of monitors will fit - not returning how many monitors that is.

Problem two is my addled brain trying to tell me that there's a complicating factor if there's an even number of monitors but as I'm working through this now, I think I might be overthinking that part.

Any help to put me on the right path here would be very, very appreciated.