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Could you tell me how to get to the baseball stadium?
Literal
Baseball-field [to-に] how go-[cond-たら] good [Q-か] teach-[humble potential-いただけ] [polite Q-ませんか].
Very polite request structure. 教えていただけませんか stacks the humble ~ていただく ('receive the favor of X') + the potential ませんか ('won't you'), giving a maximally polite 'could I receive the favor of being taught.' どうやって ('how, by what means') + ~たらよい ('should') is a common way to ask 'how should I X?' — the embedded clause is turned into the object of 教える.