ZAD 7 rozwiąż równanie {x+y=12 {10y+x+54=10x+y

x + y = 12 10y + x + 54 = 10x + y x + y = 12 / * 9 -9x + 9y = -54 9x + 9y = 108 -9x + 9y = -54 18y = 54 / : 18 y = 3 x + 3 = 12 x = 12 - 3 x = 9