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2014-11-05T19:02:19+02:00
2014-11-05T19:05:13+02:00
A+b=20 / •2 rezulta ca 2a+ 2b=40 b+c=30/ •3 rezulta ca 3b+ 3c=90 Adunam ambele relatii si iese 2a+5b+3c=130