Question 295732
You were already given an answer to this problem, but I think the tutor accidentally hit the number 9 on his puter, instead of "0".



Let's review:  The previous tutor said that if you put y = 9 into the y = mx + b format, you'd get:  y = 0x + 9.   AND since "m" represents the slope, you can see that the slope in this case, is a 0.   (The previous tutor said the slope was 9 -- and that's a typing mistake, I'm certain).


Let's discuss slopes in general:


When x equals a number, it is a VERTICAL line and the slope is UNDEFINED.


When y equals a number, then you have a HORIZONTAL line and the slope is 0.


I tell students that the way to remember that horizontal lines have a slope of zero is to think that the word "HORIZONTAL" has two letter Os in it.  I say that those Os are actually zeros, reminding you that horizontal lines have 0 as a slope. :-)  Ok, corny but it works.  


Good luck with your math and I hope this helps you. :-)