On December 31, 2012, Oakbrook Inc. rendered services to Begin Corporation at an agreed price of $102,049, accepting $40,000 down and agreeing to accept the balance in four equal installments of $20,000 receivable each December 31. An assumed interest rate of 11% is imputed. Instructions Prepare the entries that would be recorded by Oakbrook Inc. for the sale and for the receipts and interest on the following dates. (Assume that the effective- interest method is used for amortization purposes.) (a) December 31, 2012. (c) December 31, 2014. (e) December 31, 2016. (b) December 31, 2013. (d) December 31, 2015