Motion

A boy is running along a straight horizontal road with a constant speed $5 \mathrm{~ms}^{-1}$. While running he throws a stone with a velocity $30 \mathrm{~ms}^{-1}$ at an angle $60^{\circ}$ with the horizontal. Then the time of flight of the stone is: (Given $g=10 \mathrm{~ms}^{-2}$ )