1) x + y = 5; x : y = 4;
Из 1 выводим: x = 5 - y. Подставляем во второе: 5 - y = 4y;
5y = 5; y = 1;;
x = 5 - 1 = 4;
2) x - y = 2; x = 7y;
7y - y = 2; 6y = 2; y = 1/3;
x = 7/3 = 2 1/3;
1) x + y = 5; x : y = 4;
Из 1 выводим: x = 5 - y. Подставляем во второе: 5 - y = 4y;
5y = 5; y = 1;;
x = 5 - 1 = 4;
2) x - y = 2; x = 7y;
7y - y = 2; 6y = 2; y = 1/3;
x = 7/3 = 2 1/3;