The inequality has a solid-line boundary
So....we will either have ≥ or ≤
Note that the points ( 2,0) and ( 0 , -4) are on te boundary
Slope be tween these points = ( -4 -0) / ( 0 -2) = -4 / -2 = 2
Equation of the boundary line using (0 , -4) is
y = 2x - 4
But....we either have
y ≥ 2x - 4 or y ≤ 2x - 4
If we test a point which lies in the yellow region ( I'll use (3, 0) ) note that it satisfies
y ≤ 2x - 4