In this formula, b is the y-intercept. We are told that our line crosses the y-axis at (0,2.5), so the y-intercept is 2.5.y=2.5
Thus, we've found the equation of the line.
Equations in slope-intercept form follow a specific format.
In this form, m represents the slope of the line and b th e y-intercept. We are told that the slope is 0 and the y-intercept is -4. Therefore, we have that m=0 and b=-4. We can substitute these to obtain the equation of the line.