Question 317984
 3x - 4y = -17
 4x - 7y = -21
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|3 -4|
|4 -7|
Det = -21 - (-16)
Det = -5
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|-4 -17|
|-7 -21| = -x*Det
= 84 - 119 = -35
x = -7
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-21 - 4y = -17
y = -1