Effect of Price on Supply of Tires Suppose the quantity x of Super Titan radial tires made available each week in the marketplace is related to the unit-selling price by the following equation where x is measured in units of a thousand and p is in dollars.

p-1/x^2=48

How fast is the weekly supply of Super Titan radial tires being introduced into the marketplace when x = 4, p = 56, and the price/tire is decreasing at the rate of $6/week? (Round your answer to the nearest whole number.)