What was the formula used to calculate the interest expense? Step by Step, please

Bryan Company issued $780,000 of 8% face value bonds on January 1, 2016, for $763,800. The bonds are due December 31, 2018, and pay interest semiannually on June 30 and December 31. Bryan uses the straight-line amortization method. Required: Prepare the journal entries to record the issuance of the bonds and the first two interest payments.