A blue ball is thrown upward with an initial speed of 19.6 m/s, from a height of 0.7 meters above the ground. 2.4 seconds after the blue ball is thrown, a red ball is thrown down with an initial speed of 10.0 m/s from a height of 21.7 meters above the ground. The force of gravity due to the earth results in the balls each having a constant downward acceleration of 9.81 m/s2 How long after the blue ball is thrown are the two balls in the air at the same height?