A gasoline refinery found that the cost to produce 12,500 gallons of gasoline last month was $27,000. At that time, the cost was going up at a rate of $1200 per month, while the number of gallons of gasoline the refinery produced was going up at a rate of 350 gallons per month. At what rate was the average cost to produce a gallon of gasoline increasing or decreasing last month?