I am stuck with this problem help me out please!

The city of Charleston had the following sales of water for the selected months of 2016 Month Sales February $50,000 March 45,000 60.000 May 42.500 June 70.000 July 120,000 All sales are on credit. Historically, 50 percent is collected in the month of sale, 35 percent during the first month following the sale, and 15 percent in the second month following the sale. Water purchases by month are as follows: Month Sales $37,500 February March 33,750 April 45,000 May 31,875 52,500 June July 90.000