I'm studying for a test that is coming up for my accounting class and I'm solving this question from a study guide.

Quesiton 1:
On January 1, 2013 Northern Idaho Transportation Inc. issued $100,000, 12%(Contract Rate), 5 year bonds. The Market rate of interest is 15%

-The company pays interest on April 30, August 31 and December 31.
-Solve the above problem using the following: Straight line method, Effective Interest Rate Method

My textbook has explained how to do the entry for semi annual for the Straight line method which you would:

Debit interest expense
Credit Discount On Bonds payable
Credit Cash

How do I do the entry for April 30 for example? and how do I find the amount for Discount on Bonds Payable? Thanks