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 threadOka
Answer & Solution? = 15 It’s the difference between the numbers pointing at the solution. It was also the first solution I tried.
Feb 20 at 4:46pmWeb
Show threadpiyuvFeb 20
Spoiler21-13 is not 7 though
Show threadspencerwiFeb 20
That’s what I thought too, but it doesn’t work for the 7 at the end, and the caption explicitly says that the seven is not an error.
Show threadDr. BobFeb 20
I’m not sure that strategy works for the last numbers.
Show threadNaibofTabrFeb 20
This does not satisfy the lowest set. 21-13=8
Show threadstarikFeb 20
Tap for spoilerTry again. What is 21 minus 13?
Show threadArthur BesseFeb 21
NopeChuck Testa
Show threadSkankbootFeb 20
Thats wrong, the last number in the line doesn’t follow that rule.