An astronaut on the moon throws a baseball upward. The astronaut is 6 ft, 6 in tall, and the initial velocity of the ball is 40 ft per sec. The height of the ball in feet is given by the equation = -2.7t(suared)+40ft+6.5, where t is the number of seconds after the ball was thrown. After how many seconds is the ball 12 ft above the moons surface? How many seconds when it's back on the ground?