we need to find the line equation for the dashed line. Since we have 2 points of the line, its slope is

where we used the slope formula:

Then, our searched line has the form:

where b is the y-intercept. We can finde b by substituting point (0,-3) into the last equation:

then, the searched line in slope-intercept form is

Therfore, the given area can be modeled as

because when a line is dashed it doesn't belong to the given area.