7 The equation of a curve is \(\ln ( x + y ) = x - 2 y\).
- Show that \(\frac { \mathrm { d } y } { \mathrm {~d} x } = \frac { x + y - 1 } { 2 ( x + y ) + 1 }\).
- Find the coordinates of the point on the curve where the tangent is parallel to the \(x\)-axis. \(\quad\) [3]