Roman takes off in his hang glider from a peak 420 feet above the ground at 3:30 p. m. He descends at a constant rate and flies in a straight line. At 3:40 p. m. his position is 1,120 feet from the starting point horizontally and he has traveled an actual distance of 1,130 feet as shown in the figure. If Roman continues at this rate, in how many more minutes will he reach the ground level?