General

v = d/t
d = 6m, t = 2s
v = 6/2
v = 3m/s OR ms-1

at t=2s, ball has travelled 6m
d = 6 + (3*2)
d = 12m

I suppose that would be correct.

Acceleration supposed to be gravity = 9.81 if its free fall
But question doesnt seem to be right that way
d = vt + 1/2 at^2
but v initial there is 0m/s so ignore it
d = 1/2 at^2
from initial statement
6 = 1/2 a x 2s^2
so acceleration is 3m/s2
then putting it in formula again
d = 1/2 x 3m/s2 x 4s^2
d = 24m

Edit: sry its wrong, I still need practice understanding English right
yea velocity to the x direction wont change so double the time means double distance unless it hits the ground b4 that

@TeenyRikku

Ok thanks. Ill try that out.

i think i did a problem similar to this but it feels like that was a long time ago
im not sure but maybe its d= V1(t)+1/2a(t)^2
d= 0(4)+1/2(9.8m/s^2)(4)^2
d= 82.4m?