Question 136195
.1..3..6
-4 -9..3 
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Add 4 times the 1st row to the 2nd row to get:
.1..3..6
.0  3..27
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Divide thru the 2nd equation by 3 to get:
 
.1..3..6
.0  1..9
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Add -3 times the 2nd row to the 1st row to get:
.1..0..-21
.0  1..9
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Cheers,
Stan H.