Question

система x+y=30, x-y=20;

Answer 1

x+y=30, x-y=20; x =30-y 30-y-y=20 30-2y=20 2y=10 y=5 x=30-5 x=25

Answer 2

x+y=30, x-y=20; Сложим уравнения 2х=50; x=25; 25+у=30 y=5; Ответ: (25;5)