Math is not mathing (need an explanation with colors)

Apologies for the poor quality of the picture.

I’m not the most experienced and knowledgeable LoL player out there, but in my years of experience with math I’ve learn that 0+38=38, not 33.

I didn’t get promoted in this game, but I lost the two previous games - right after the promo. Is it the demotion prevention thingy that is applying here?

I’m not complaining by any means, but I’m really curious about how Riot doesn’t math.

Thanks a lot for your kind responses!!