Răspuns:
[tex]\frac{x}{y} =\frac{3}{5} =>x=\frac{3y}{5} \\ \\\frac{5x+7x}{9x-5y} =\frac{12x}{9x-5y} \\\\\frac{12*\frac{3y}{5} }{9*\frac{3y}{5} -5y} =\frac{36y}{5} :(\frac{27y}{5} - ^{5} )5y)=\frac{36y}{5} :(\frac{27y-25y}{5} )=\frac{36y}{5} :\frac{2y}{5} =\frac{36y}{5} *\frac{5}{2y} =\frac{36y}{2y} =18[/tex]
