A baseball player hits the ball and then runs down the first base line at 21 ft/s.21 ft/s. The first baseman fields the ball and then runs toward first base along the second base line at 15 ft/s.15 ft/s. An illustration shows a baseball diamond with two players running towards first base along. The paths are perpendicular to each other. The distance between one player and first base is labeled x and the distance between the other player and first base is labeled y. The distance between the players is labeled d. Determine how fast the distance between the two players is changing at a moment when the hitter is 16 ft16 ft from first base and the first baseman is 12 ft12 ft from first base. (Use decimal notation. Give your answer to one decimal place.)