First, let's calculate the slope of the line.
To do so, we'll need two points that belong to the line. Taking a look at the graph, we can obtain points

This way, we'll get:

Now, notice that point

is also the y-intercept of the line.
This way, the equation of the line in the slope-intercept form ( y = mx + b) is:

Answers:
1. m = -3
2. y-intercept = 4
3. Equation: y = -3x + 4