It was + that was misused. However, if you said
2 v 3 = 10 ... probably nobody would get it!
Or worse ... f(2,3) = 10
Anyway, it is definitely a math problem, but the phony + did slow me down, I was thinking it might be one of those "count the letters" things, or something.
( It took me exactly 1:59 :-)
Look just at the pattern of the numbers on the right side of the “=” sign as they relate to each other. Just because numbers are used in a sequencing problem doesn’t make it a valid math problem. The “=” sign was not correct in any of the equations.