Parse ascii art math!
APL (Dyalog Unicode), 46 44 bytes



'/(80-)63+92145*7'[16|43|25⊥¨(×⊆⊢)2⊥' .\'⍳⎕]


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⎕ evaluated input, must be a character matrix

' .\'⍳ replace spaces with 0, .s with 1, \s with 2, and everything else with 3

2⊥ base-2 decode the columns

(×⊆⊢) split on zeroes

25⊥¨ base-25 decode each group

16|43| mod 43, mod 16

'/(80-)63+92145*7'[ ] use as indices in the given string