Meaning?

To "know one's way around something" means to understand or to be familiar with it.

"scores" presumably means musical scores (written music).

"In high school guitar and drums" is not a proper sentence. Some words appear to be missing.

Anonymous. I know my way around scores.

Decker is an expert at reading musical notation.

Thanks for both replies. You are right. A coma between The words "school" and "guitar" is missing and has not been typed. But still the phrase seems doesn't seem proper to me, because in my view we can not say in guitar and in drums. I appreciate further comments. May be I am mistaken.

Thanks

AnonymousThanks for both replies. You are right. A coma between The words "school" and "guitar" is missing and has not been typed. But still the phrase seems doesn't seem proper to me

A comma will not make it a grammatically complete sentence. However, it could still make sense in context, with the missing words implied by what has previously been said. For

Your reasoning and deduction is absolutely right. A further detailed text in the book reads as follows;

"How do you know? Did you play music?"

Decker nodded. "In high school, guitar and drums"

Thanks