Answer:
y = -3x + 7 (above)
Explanation:
To add on, the person above me is correct. The equation of the line is in mx + b, where m is slope and b is the y-intercept.
We see the line intercepts the y axis at (0,7). Therefore the equation is y= mx +7
Now we look for m, the slope. If you may remember slope is also change in y over change in x, or rise/run. If you look at the graph, for each unit to the right, the line drops 3 units(it goes down, so negative). Therefore the slipe would be -3/1, or -3.
Plugging that in,
y = -3x + 7