Projectile motion problem...urgent...please help fast

Let the initial velocity of the projectile be  and its initial angle of projection 
Since there is no acceletaion in the horizontal direction
Therefore, the horizontal velocity will be constant
The horizontal component of the velocity

The vertical componenet

The projectile covers 120 m distance with the velocity  in time  seconds
Therefore,

 ............. (1)
The vertical height obtained by projectile is given by

or, 
Since this is a quadratic equation in t therefore for any particular height there will be two values of t
we know that for the given height in the question the values of t are 2 seconds and 6 seconds
Hence from the quadratic equation
Sum of roots = -(coefficient of t)/(coefficient of t^2)
or, 

 ................(2)
Dividing eq (2) with eq (1) we get