Atomic Floor Cleaner Compound

I was getting ready to wax the floor the other day at one of our rental properties, when I noticed some stubborn stains on the vinyl tile floor. There were square darkened areas where the previous tenant had laid some rubber-backed floor mats:
So, I stripped off the wax, and thoroughly cleaned the floor, but the stains remained. All of my commercial-grade big-guns would not blast out the stain.
I did a little research, and found the cause - not the tenant, but the manufacturer of the rugs. Have you noticed that the backing of rubber-backed rugs does not deteriorate and crumble as much as in the old days? That's because the manufacturers treat the backing with ANTI-OXIDANTS, which retard the deterioration of the rubber. And they react with vinyl tile, even through many coats of floor wax, by osmosis. And there was even a little-known cure, using safe planet-friendly ingredients that can be found in any kitchen cabinet: lemon juice and baking soda. (if you look at the first picture again, you'll see I just had some lying around in the doorway!).And I followed the instructions, first adding about half a box of baking soda, and then enough lemon juice to form a paste.
They didn't say that this would cause a reaction akin to cold nuclear fusion, but, hey, it was the most exciting thing that happened that day. Janitors don't get out much, and they have to get their entertainment wherever they can.
So I applied the glop, which smelled good enough to eat, all over the floor, and spread it around with my Power Flite floor scrubber. Here's a cockpit view:
I let the paste set overnight on the floor, as suggested, and the following day, I eagerly mopped up the dried mixture to reveal:
Nothing. The atomic home-made Internet Compound for the Elimination of Anti-Oxidants did nothing. In all fairness, in subsequent days, I also tried the Miraculous Oxi Substance with the same results. Looks like the dead guy couldn't help me either.

So, last night I started waxing, and the stains will be a little easier to sell to prospective tenants under three coats of gleaming fresh-smelling floor wax. The only other option is to replace the tiles. So, the Serenity Prayer Solution it is! Learn to accept the things the landlord is no f@#$g way going to change. It's a very clean and shiny stain. Or get a throw rug! With a nice rubber backing treated with anti-oxidants so that the backing will not deteriorate. This is how the world goes 'round.