Answer: zero slope
Explanation: The equation y = -4 can be thought of as y = 0x - 4.
So our line has a slope of 0 and a y-intercept of -4.
This line is a flat line or horizontal.
In fact, when the equation of any line reads y = <em>a number</em>, its slope
will always be 0 because it's a horizontal line.
So, this line has a slope equal to <em>zero</em>.
