\\ 50=-9 x-2 y \end{array} (7,-4) ; \begin{array}{l} 9 b+4 a=-8 \\ 6 a+5 b-42=0 \end{array} (-3,-2) ; \begin{array}{l} -7 c-4 d=29 \\ 3 c=-7+d \end{array} Check whether (6, 9) is a solution of the systems of linear equations. \begin{array}{l} s+7 t=69 \\ 6 t+4 s=78 \end{array} \begin{array}{l} -2 p+5 q=34 \\ -7 q=-61-8 p \end{array} Write a system of linear equations that has the solution (4, 3).
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