ANSWER
m = undefined
b = doesn't exist
EXPLANATION
x = 5 is a vertical line where in all points x is 5. Therefore, if we use the formula for the slope:
[tex]m=\frac{y_1-y_2}{x_1-x_2}[/tex]The denominator will always be 0. Since we can't divide by 0, the slope is undefined.
Since it's a vertical line, there's no y-intercept. This is because the y-intercept is the value of y when x = 0 and in a vertical line x has always the same value: in this case, 5.