7x－3y=－6则：35x－15y=－30 ------------------(1)4x－5y=－13则：12x－15y=－39 ------------------(2)(1)－(2),得：23x=9x=9/23以x=9/23代入7x－3y=－6中,得：－63/29－3y=－6y=67/23则：x=9/23、y=67/23...