The first inequality is $x+y \leq 9 $----(1)
Consider the equation $x +y =9$
The points (9,0) and (0,9) satisfy the equation.
The graph of the line is drawn as shown.
The line divides the xy -plane into two half planes .
Consider the point (0,0) We see that
$0+0 \leq 9$
$0 \leq 9$ is true.
Thus the inequality $x+y \leq 9$ represents the region below the line $x+y =9$ containing the point (0,0) including the line .
The second inequality $ y > x$ ----(2)
consider the equation $y=x$
The points $(1,1) ,(0,0)$ satisfy the equation.
The graph of the line $y=x$ is drawn using dotted line as shown .
The graph divides the xy plane into two half planes.
consider the point $(1,0) $ we see that
$ 0 > 1$ is false.
Thus the region represented by the inequality $y >x$ is above the line not containing point (1,0) (excluding the line y=x)
The third inequality $x \geq 0$
The inequality represents the region right of the y-axis (including y axis )
The solution of the system of inequality is represented by the common shaded region including the points on the line $x+y =9$ and $x=0$ and excluding the points on the line $y=x$.