Have had this math puzzle that I have been unable to solve for a while.
Each leter is a number between 1-9. No letter uses the same number twice (aka if B is 3 D can't be 3 also). The ? mark represents an unknown letter (as in it could be any letter).
$$A + B + C + D = EF$$ $$G + F + E + H = CJ$$ $$B + G + J = \;?D$$