When you see a slope that is undefined, that means that the line is vertical.
(5,-2); 5 is the x - coordinate and -2 is the y - coordinate
Slope - intercept form: y = mx + b
As shown above, the equation would've been written in slope - intercept form (given above), where 'm' represents the slope and 'b' represents the y - intercept. In this case, however, the slope is undefined.
In this equation, you're looking for the x - intercept of the equation. Therefore, the x - intercept is 5.
x = 5