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20240060010
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20240060010
Posted:
Mon Feb 05, 2018 9:38 pm
by
ada
$\begin{align}3a-b+2c-d&=18\\7a+b+3c+2d&=54\\2a+b+8c+6d&=57\\4a-b-3c+d&=7\end{align}$