It was recently reported in the financial press, that a major retailer spent $$29$ million an hour on cashier wages. Concerned about future increasing labor cost assume that this retailer installs self$-$checkouts for the customers to use in their purchases. The initial cost of these machines is $$50,000$ and these machines have a life of eight years. The yearly savings in cashier labor cost is $$70,000,$ the additional surveillance cost is $$10,000$ per machine, and the additional theft cost is $$10,000$ per machine. Using a $7\%$ cost of capital and ignoring depreciation and taxes $($until covered in chapter $8),$ the net present value of these self$-$checkout machines is $\_\_\_\_\_\_\_\_\_$