The directions are to write a paragraph explaining how to deduce what you want to prove from the given information.
I'm confused,so any help appreciated!
Here's a formal two-column proof, I'll let you translate it into an English paragraph...
$\displaystyle
\begin{array}{ll|l}
&Statement&Reason\\
\hline\\
(1)&\overline{AT}\cong \overline{GS}, \overline{AT}\| \overline{GS} &Given\\
(2)&\angle SGT \cong \angle ATG&Alt.\ Int.\ Angles\\
(3)&\overline{GT}\cong \overline{GT}&Reflexive\ property\ of\ \cong\\
(4)&\triangle GAT \cong \triangle TSG&1,\ 2,\ 3,\ SAS
\end{array}
$