How much time needs to pass for an A/R account to be considered delinquent? 

Asset means anything that can be converted into cash. Here in banks, the loans disbursed by Bank to its customers is considered as assets because when they are cleared by them, then they are directly converted to cash.

Goods that are excludable include both private goods and natural monopolies.

Money market instruments are debt securities that generally give the owner the unconditional right to receive a stated, fixed sum of money on a specified date.

There are several money market instruments in most Western countries, including treasury bills, commercial paper, bankers' acceptances, deposits, certificates of deposit, bills of exchange, repurchase agreements, federal funds, and short-lived mortgage- and asset-backed securities.

Assets minus liabilities equals Equity.

Other things the same, when the interest rate rises people would want to lend more, making the quantity of loanable funds supplied increase.

The journal entry to record a credit sale is Accounts Receivable. Credit sale is nothing butthe customers pay at the time of buying.