This is what I did so far but I am having trouble with the last entry ?

[The following information applies to the questions displayed below The following events occur for Morris Engineering during 2012 and 2013. Its first two years of operations. February 2, 2015 Provide services to customers on account for $36.200. July 23, 2015 Receive $25,500 from customers on account. December 31, 2015 Estimate that 25% of uncollected accounts will not be received. April 12, 2016 Provide services to customers on account for $49,200. June 28, 2016 Receive $6,000 from customers for services provided 2015. September 13. 2016 Write off the remaining amounts owed from services provided in 2015 October 5, 2016 Receive $43,500 from customers for services provided in 2016. December 31, 2016 Estimate that 25% of uncollected accounts will not be received