Answer:
7
Step-by-step explanation:
The triangle is a special right triangle.
Since it has a 45° in one of the two unknown angles, the other angle is also 45°. This is called a 45-45-90 right triangle.
The rule for that special triangle is that the legs measure the same while the hypotenuse measures a multiplication of √2.
Since one leg is labeled 7 units, the other (which is x) is labeled 7 too.