Question c185d9c2

Advanced Math - Nonlinear equations in one variable and systems of equations in two variables

$y equals, x squared plus 2 x plus 1, and, x plus y plus 1, equals 0$

If $the ordered pair x subscript 1 comma y subscript 1$ and $the ordered pair x subscript 2 comma y subscript 2$ are the two solutions to the system of equations above, what is the value of $y subscript 1, plus, y subscript 2$ ?