From the graph, we can see the line is passing through the points (-3,0) and (0,-3).
So the x-intercept of the graph is -3 and y-intercept of the graph is -3.
The slope of the line passing through (-3,0) and (0,-3) is
[tex]m=\frac{-3-0}{0-(-3)}\Rightarrow m=\frac{-3}{3}\Rightarrow m=-1[/tex]
Hence slope of the line is m= - 1.
Now we know that equation of a straight line with slope m and intercept c is
[tex]y=mx+c[/tex]
Hence the equation is
[tex]y=-x-3[/tex]
