#1
The x axis of the trajectory will show the displacement in X direction only
So it is the Horizontal range
Correct answer would be
Displacement in the horizontal direction(my guess)
2
The stone is projected horizontally at height 64.8 m
now we can use kinematics in Y direction
[tex]\Delta y = v_y * t +\frac{1}{2} gt^2[/tex]
now we have
[tex]64.8 = 0 + \frac{1}{2}*9.8*t^2[/tex]
[tex]t = 3.64 s[/tex]
so here it will fall in the air for time t = 3.64 s