Williams Auto has a machine that installs tires. The machine is now in need of repair. The machine originally cost $11,100 and the repair will cost $2,100, but the machine will then last two years. The variable (labor) cost of operating the machine is $0.90 per tire. Instead of repairing the old machine, Williams could buy a new machine at a cost of $6,100 that would also last two years; the labor cost per tire would be reduced to $0.40 per tire. a. Determine the total (two-year) cost for both repairing and replacing the machine.