Final answer:
Under a purely flexible exchange rate regime, the balance of current accounts plus the balance of capital accounts equals the negative balance of official reserve accounts.
Step-by-step explanation:
When the balance of payment (BOP) accounts are recorded correctly under a purely flexible exchange rate regime, the equation that stands correct is BCA (balance of current accounts) + BKA (balance of capital accounts) = - BRA (Balance of official reserve accounts). This identity signifies that if a country has a surplus in its current and capital accounts (BCA + BKA > 0), it must be accumulating reserves, whereas a deficit (BCA + BKA < 0) would imply it's spending reserves. This directly correlates with the concepts of trade balances and international flows of financial capital; where a current account surplus indicates that the country is a net lender internationally, whilst a deficit indicates it is a net borrower.