The equation is y < x/3 + 3.
How to determine equation of inequality from a graph.
From the the graph
The slope = change in y/change in x
Locate points (-9,0) and (9,6).
m = y2-y1/ x2-x1
= 6 - 0/9 - (-9)
= 6/9+9
= 6/18 = 1/3
They y-intercept is 3. The point where y(x) crosses the y-axis.
Let's apply equation of a line
y = mx + b
where
m is slope
b is y-intercept
Substitute
y = x/3 + 3.
The line is broken, meaning that the boundary value is not included in the solution.
The part/region below the line is shade. That is the solution region is less than the value of the boundary line
So, the equation is y < x/3 + 3