Answer:
Interest Expense $6,446,360
Interest Payable $7,000,000
Explanation:
Interest Expense for the year =
Issued amount * Effective interest rate * 
$644,636,000 * 0.06 * 2/12 = $6,446,360
Interest Payable =
Face Value of the bond * Interest rate * 
$600,000,000 * 0.07 * 2/12 = 7,000,000