The management of Blues Bar believes that the number of events held each month is a measure of activity for total clean-up cost. The figures below are the total clean-up and cost for the last four months.
# of sporting events cost total clean-up
july 28 $30,900
august 34 $34,200
September 16 $20,700
October 22 $28,200
Estimate Blues Bar's cost formula for monthly clean-up cost using the least-squares regression method (please show work by providing a spreadsheet/graph)