so hmmm notice the picture below
"x" being how many seconds the object was going
and when y = 0, the object hits the ground, either on the moon or on earth
so, if we set y = 0 on each equation, we'll know when that happen, how long of a "x-value" or seconds it took
[tex]\bf \begin{array}{llll}
\textit{on the moon}\\\\
h=-2.7t^2+96t\implies 0=t(96-2.7t)
\end{array} \quad
\begin{cases}
0=t\\
-------\\
0=96-2.7t\\
2.7t=96\\
t=\frac{96}{2.7}\\
t\approx 35.\overline{55}
\end{cases}\\\\
-------------------------------\\\\
\begin{array}{llll}
\textit{on earth}\\\\
h=-16t^2+96t\implies 0=t(96-16t)
\end{array} \quad
\begin{cases}
0=t\\
------\\
0=96-16t\\
16t=96\\
t=\frac{96}{16}\\
t=6
\end{cases}[/tex]