This looks the equation of motion for the trajectory of a particle projected vertical upwards under earth's gravity. When solved, t is the time in seconds for the particle projected at a speed of 180m/sec to reach or fall to a height of 300m. So 9.81t^2-180t+300=0. Using the quadratic formula: t=(180+sqrt(32400-1200*9.81))/19.62=16.495 or 1.854.