XYZ bills its clients on the first of the month. For example, any sale made in the month of July is billed August 1 and is due September 1. Clients traditionally pay as follows: 50% by the end of the first month , 40% by the end of the second month , 8% by the end of the third month , and 2% default on their bills. What is the dollar value of January billings collected in April?

First-Quarter Sales			Second-Quarter Estimated Sales
January	February	March	April	May	June
$ 44,000	$ 37,000	$ 48,000	$ 49,500	$41,000	$ 31,500

I got the answer of $ 3,520

Please show the solution.