During 2005, Plano co. purchased 2,000, $1,000, 9% bonds. The carrying value of the bonds at December 31, 2007 was $1,960,000. The bonds mature on March 1, 2012, and pay interest on March 1 and September 1. Plan sells 1,000 bonds on September 1, 2008, for $988,000, after the interest has been received. Plano uses straight-line amortization. The gain on the sale is? Answer = $4,800. Question: What formula or approach do I use to arrive at this answer? I'm especially having trouble determining how long the bond was held prior to the purchase date