-- The "y-intercept" is the point where the graphed line crosses the y-axis.
-- At every point on the y-axis, x = 0 .
-- So the y-intercept of the line represented by an equation is the value
of 'y' when x = 0.
y = -3x - 5
When x= 0 : y = -3(0) - 5 = -5 .
The y-intercept of the line represented by that equation is -5 .