A city is considering a new $50,000 snowplow. The new machine will operate at a savings of $600 per day, competed to the equipment presently being used. Assume the minimum a rate of return (interest rate) is 12% and the machine's life is 10 years with zero resale value at that time. How many days per year must the machine be used to make the investment economical? 32.1 days/year 14,7 days/year 10,2 days/year 21,3 days/year