He used the method of scratching into a copper sheet. It is called Intaglio. Intaglio is a technique in printmaking. Copper and zinc are the two materials that are normally used with this kind of medium. Another example of this are collagraphs.
Balance sheet is a financial statement that lists all the assets, liabilities, and owner's equity.
Assets = Liabilities + Owner's Equity
Liabilities = Assets - Owner's Equity
Owner's Equity = Assets - Liabilities
I think the answer is Chord.
