Several years ago, the City of Russell issued $7 million of 6 percent serial bonds at 101. Principal payments of $350,000 are due each June 30 for 20 years. Interest on the bonds is payable each December 31 and June 30. As of June 30, 2015, the city has not paid the June 30 principal and interest payment. The amount of interest payable (assuming an outstanding balance of $4,000,000 of bonds) that should be included on the balance sheet for the debt service fund of the City of Russell at June 30, 2015 is $168,000. How to calculate amount of $168,000?