[latex]egin{cases}frac{x+1}{3} -frac{{y+2}}{4}=frac{2(x-y)}{5}/cdot 60\ frac{x-3}{4}-frac{y-3}{3} =2y-x/cdot 12end{cases}\ \egin{cases}20(x+1) -15(y+2)=24(x-y)\ 3(x-3)-4(y-3) =24y-12xend{cases}\ \egin{cases}20x+20 -15y-30=24x-24y\ 3x-9-4y+12 =24y-12xend{cases}[/latex] [latex]egin{cases}20x-15y-24x+24y=30-20\ 3x-4y -24y+12x=-12+9end{cases}\ \egin{cases} -4x+9y=10/cdot 15\ 15x-28y=-3/cdot 4end{cases}\ \egin{cases} -60x+135y=150\ 60x-112y=-12end{cases}\-----------\23y=138/:23\[/latex] [latex]y=6\ \-4x+9cdot 6=10\ \-4x+54=10\ \-4x=10-54\ \-4x=-44/:(-4)[/latex] [latex]x=11\ \egin{cases} x=11\ y=6end{cases}[/latex]
