**Question **# Solve each system of equations using elimination method. \begin{array}{l}
2 x+5 y=20 \\
6 x-5 y=12
\end{array} \begin{array}{l}
3 p+4 q=-3 \\
-p+4 q=-15
\end{array} \begin{array}{l}
-7 a+3 b=15 \\
7 a-6 b=-3
\end{array} \begin{array}{l}
u+v=11 \\
-u+v=9
\end{array} \begin{array}{l}
5 r+8 s=3 \\
4 r+8 s=-4
\end{array} \begin{array}{c}
-9 c-2 d=8 \\
-9 c-d=6
\end{array} \begin{array}{l}
m-4 n=13 \\
m-6 n=12
\end{array} \begin{array}{l}
3 s+7 t=18 \\
3 s-4 t=-48
\end{array}