Answer: The given line is vertical. The slope is undefined
Step-by-step explanation: If you plot x = -7, you would get a vertical line because all the y values are changing but the x value isn't. Due to this, there would be an undefined slope. If you had a horizontal line, such as y = 5, the slope would be 0 because the x values are changing but there is no y value change.
Think about it like this, if you use rise/run to find slope and you plot x = -7, you are rising forever but running 0 spaces. Therefore, the rise/run formula could be 5/0 or 7/0, but those values are undefined.
Hope that helps!