Ответ:

Вычитаем из 2-го уравнения 1-ое уравнение .

[tex]\left\{\begin{array}{l}\bf x+y=3\\\bf x+2y=2\end{array}\right\ \ \left\{\begin{array}{l}\bf x+y=3\\\bf (x+2y)-(x+y)=2-3\end{array}\right\ \ \left\{\begin{array}{l}\bf x+y=3\\\bf y=-1\end{array}\right\\\\\\\left\{\begin{array}{l}\bf x-1=3\\\bf y=-1\end{array}\right\ \ \left\{\begin{array}{l}\bf x=4\\\bf y=-1\end{array}\right\ \ \ \ \bf Otvet:\ (\, 4\, ;-1\ )\ .[/tex]