gigastasioFeb 20

I've had this puzzle on my phone for years. Every few months I'd glance at it and try and solve it. Last night, as I was eating dinner, I finally figured out the answer!

https://sh.itjust.works/post/55641581

Show threadOkaFeb 20
Answer & Solution? = 15 It’s the difference between the numbers pointing at the solution. It was also the first solution I tried.
Show threadpiyuv
Spoiler21-13 is not 7 though
Feb 20 at 4:52pmWeb