How do I Solve for t in a Projectile Motion Equation?

[Tatjana]

Homework Statement

The given equation is:
0 = vt-1/2at^2
and you must solve for t.

Homework Equations

There's a question similar to this one, d=ut+1/2at^2, but there's an extra variable so you are able to use the quadratic formula. In this case, I'm not quite sure if I'm solving the question correctly.

The Attempt at a Solution

I've tried running through numerous solutions but none of them seem quite right. Here's my attempt, at least.
0=vt-1/2at^2
v=t-1/2at^2
-2av=t-t^2
sq.root(-2av)=t

What am I doing wrong here? I've gone about a year without math, and these are just some introductory algebra questions to 'warm us up' for our physics course, so I think there are a lot of key things that I've forgotten about that could help me solve this question. (BTW, this is a grade 11 university physics course)

 

[glueball8]

$$A-B=0$$

add B to both side to get

$$A-B+B=B$$

and -B+B is usually called zero.

 

[Synix]

I have the same question, you're reply doesn't really help. It's clear that she has an understanding of what to do and she gave you her attempt... Going over simple rules won't help if she doesn't know where she went wrong.