\(\left\{{}\begin{matrix}\%A+\%G=50\%N\\\%A.\%G=6\%N\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}TH1:\left\{{}\begin{matrix}\%A=\%T=20\%N\\\%G=\%X=30\%N\end{matrix}\right.\\TH2:\left\{{}\begin{matrix}\%G=\%X=20\%N\\\%A=\%T=30\%N\end{matrix}\right.\end{matrix}\right.\)
\(TC:A+G=50\%\\ \Leftrightarrow A=50\%-G\)
\(A\cdot G=6\%\)
\(\Leftrightarrow\left(50\%-G\right)G=6\%\)
\(\Leftrightarrow-G^2+50\%G-6\%=0\)
\(\Leftrightarrow\left[{}\begin{matrix}G=X=20\%\Rightarrow A=T=30\%\\\\G=X=30\%\Rightarrow A=T=20\%\end{matrix}\right.\)