physics acceleration

A tennis ball is released from rest at a height h = 32 m above the ground. The ball collides with the ground and bounces up at 75 % of the impact speed the ball had with the ground. The collision with the ground is nearly instantaneously. A second ball is released above the first ball from the same height the instant the first ball loses contact with the ground. Calculate the time when the two balls collide in seconds. (Take g = 9.8 m/s