17)

The triangle on the right has angles $$70$$ and $$90$$ degrees. The third angle is $$180 - 90 - 70 = 20$$ degrees. The angle $$x$$ is part of the larger triangle. The larger triangle has angles $$20$$, $$70$$, and the angle at the top. The angle at the top is $$90 - 20 = 70$$ degrees. The angle $$x$$ is an exterior angle. The two opposite interior angles are $$70$$ and $$20$$. So, $$x = 70 + 20 = 90$$.
Answer: $$x = 90$$.