Science
posted by Jessica on .
a ball is thrown upward at a speed of 12 m/s. It will reach the top of its path in about:
a) 0.6 sec
b) 1.2 sec
c) 1.8 sec
d) 2.4 sec
Please explain how you find the answer!!! I cannot figure it out

speed at the top is zero.
Vf=vi9.8t
0=129.8t
t= about ... 
I learned the formula to be v=gt...why are you subtracting?
Also what is vf and vi? 
vf= final velocity, which is zero at the top.
vi is initial velocity.