First the slope must be found.
The graph goes from (0,300) to (450,0), so the slope is falling by 300 every 450 units
numerically, the slope is
[tex] \frac{ - 300}{450 } [/tex]
which simplifies to
[tex] \frac{ - 2}{3} [/tex]
the y intercept is visible on the graph as 300, so now we plug in what we know to slope intercept form
y = (slope) x + y-intercept
[tex]y = \frac{ - 2}{3} x + 300[/tex]
