1) Solve simultaneously:
Initial matrix
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Subtract 3 line twos from line 1
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Subtract 4 line twos from line 3
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Subtract 11/7 line ones from line 3
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Multiply line 3 by 7/72
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Substitute the value of w into lines 1 and 2
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Add 25 to line1 and subtract 7 from line2
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Multiply line one by 1/7
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Substitute the value of v into line 2
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Add 12 to line2
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Switch lines 1 and 2
Beautiful latex, angel.white
An alternative approach that avoids explicitly using matrices:
(1) - 3 x (2): 7v - 25w = 17 .... (A)
(3) - 4 x (2): 11v - 29w = 37 .... (B)
Now solve (A) and (B) in the usual way (I'd suggest elimination method): v = 6, w = 1.
Now sub v = 6 and w = 1 into either (1), (2) or (3).