Question

1).{х = 3y - 7,
{2x+3y = 7,

2)
{2х + 9 y = 13;
{x – 3 y = 11?​

Answer 1

1)2•(3y-7)+3y=7
6y-14+3y=7
9y=21
y=21/9=7/3
Теперь подставляем
x=3•7/3=-7
x=-14