How I do I right this y = mx + b equation for this graph and what does it mean? Also the slope and y intercept from the other screen was: -3 for slope and 0 for Y intercept.

SOLUTION:
We are to write the equation the equation of the line in the form y = mx + b.
From the information given in the question, the slope = -3 and y - intercept = 0.
In the formula above, m is the slope and b is the y intercept.
[tex]\begin{gathered} y\text{ = mx + b} \\ y\text{ = (-3)x + 0} \\ y\text{ = -3}x \end{gathered}[/tex]CONCLUSION:
The equation of the line with slope of -3 and y - intercept of 0 is y = - 3x.