Since the slope and the y-intercept for the equation of y = mx + b doesn't exist, you don't need to include it.
y = mx + b
Without the m and b, which are the slope and y-intercept, you are left with x.
Then, you need to figure out whether the line is horizontal, or vertical.
If the line is vertical, you keep the x, and find out the value x is on for every point of y.
If the line is horizontal, you keep the y, and find out the value y is on for every point of x.
Since the line is vertical, we can use x = ?
The line is always at x=2, no matter what the y-value is, so the final equation would be x=2.
I hope this helped you! :)