The relevant formulae
(2) S = ut + ½at²
and (3) v²=u²+2aS
Where S=displacement, u=initial velocity, v=final velocity, t=time, a=acceleration.
When a projectile is fired upward, the gravitational force of earth tends to retard the motion of the projectile. The acceleration due to gravity,
Since this acts against the upward motion, a has to be taken as negative.
Moreover, all the quantities should be converted to SI Units.
With these hints, please try to solve the problem.