Answer:

Explanation:
We know that one angle is 45 degrees and another is 90 degrees. That means the third angle is also 45 degrees, because all angles in a triangle add up to 180 degrees. This means that the triangle we are dealing with is an isosceles right triangle, meaning the the 2 equal legs form a right angle and are equal in length. If one leg is 6, the other leg must be 6, too.
Then, by the Pythagorean theorem, x=
=
.