Can someone explain these calculations to me? Specifically I am stuck on where the 3/50 is coming from.

Question 4 1/ 1 pts On October 1, 2015, Best, LLC purchased to hold to maturity 500, $1,000, 9% bonds for $520,000. $15,000 was also paid for accrued interest. On December 1 and June 1, interest was paid. The bonds matured on December 1, 2016. Best uses straight-line amortization. How much should be reported in Best's 2015 income statement from this investment, ignoring income taxes? O $11,250 $10,050 O $12,450 $13,650 ($500,000 *.09 * 3/12) - ($20,000 * 3/50) = $10,050