x=2. -5/6 have a great rest of your day
The '68-95-99.7' rule says
-About 68% of values fall within one standard deviation of the mean.
-About 95% of the values fall within two standard deviations from the mean.
-Almost all of the values — about 99.7% — fall within three standard deviations from the mean.
Here 
Therefore, the probability

The required probability

Take a pencil put it on the paper then make sure the ink is on the paper then write
The equation would be -9+-9 = -18
Notice how points T and Z are vertically aligned, or vertically lined up. This is where the graph fails the vertical line test.
The input x = 2 leads to the outputs y = 3 and y = 5 (which are the y coordinates of points Z and T in that order).
A function is only possible when any given input leads to <u>exactly one</u> output only. It would be like saying "the conversion function from Celsius to Fahrenheit has 0 degrees C convert to both 32 degrees F and 50 degrees F at the same time". But such a statement makes no sense and it's not useful. So this is one example of why having one output makes sense for a function.
In short, we need one output for any given input. But the input x = 2 leads to more than one output. That's why we don't have a function.