so you know the horizontal acceleration is zero
integrating this you can find the horizontal velocity as 
vh=Vcos(α)
V = initial velocity   1200 ft/sec
the angle is 45 so you have 
vh=1200cos(45)
if you integrate this equation with respect to time (t) you get the horizontal displacement equation. 
the initial condtions for the horizontal displacement seem to bet at t = 0, x = 0
then when you get the equation, just substitute t = 2 and evaluate