expertSalim Service company owns several taxis that were purchased four years ago for $$21000$ each. The current market value is $$12000$ each. If they are kept for another $8$ years, they can be sold for $$2000$ each. The annual maintenance cost per cab is $$1000$ a year. Salim Service is looking at replacing the cabs with the option to lease new cabs at an annual cost of $$9000$ per year per cab which includes free maintenance. How much more would it cost them per year to switch to leasing? Assume an interest rate of $10\%.$

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