need to know how to do it

A body be projected horizontally from a certain height ‘y’ vertically above the ground with initial
velocity u. If friction is considered to be absent, then there is no other horizontal force which can affect
the horizontal motion. The horizontal velocity therefore remains constant and so the object covers equal
distance in horizontal direction in equal intervals of time.
(1) Trajectory of horizontal projectile : The horizontal displacement x is governed by the
equation
x = ut 
u
x
t  …. (i)
The vertical displacement y is governed by ...