Aha, here is the mathematician's trick to this problem!
You see, it is a model. Notice how there's no words to accompany the "problem" on the board?
Which means that even though it LOOKS like a triangle to our eyes, it doesn't have to be. In fact, it cannot be, judging by the right angle and congruency lines.
And models do not have to be to scale or accurate to what they are representing, it just really helps a lot if they are.
In other words, this image is clearly either an unclosed polygon or has more than three sides. These things are simply either too subtle to see or not represented in the model!
The answer is that X equals 19, since despite the inaccuracy of the model, the standard symbolization is still there to indicate that X is equal to the other visible sides.