Question 111412
Well you've got t on both sides now. 
How about if we start over and re-write the equation?
{{{(g/2)t^2+v[0]t=s}}}
{{{(g/2)t^2+v[0]t-s=0}}}
or maybe a little more clearly
{{{at^2+bt+c=0}}}
where a,b, and c are constants
{{{a=g/2}}}
{{{b=v[0]}}}
{{{c=-s}}}
Does that help?
{{{at^2+bt+c=0}}}
Could you solve for t now?
If you still need help, please re-post a question.