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[tex]\it 3m - - - - - -- 12z\\ \\ 9m - - - - - - - - xz\\ \rule{150}{0,7}\\ Avem\ propor\c{\it t}ionalitate\ invers\breve a \Rightarrow 3\cdot12=9\cdot x \Rightarrow 33=9\cdot x\Big|_{:9} \Rightarrow x=4 \ zi\ell e[/tex]
[tex]\it 3m - - - - - -- 12z\\ \\ 9m - - - - - - - - xz\\ \rule{150}{0,7}\\ Avem\ propor\c{\it t}ionalitate\ invers\breve a \Rightarrow 3\cdot12=9\cdot x \Rightarrow 33=9\cdot x\Big|_{:9} \Rightarrow x=4 \ zi\ell e[/tex]