Answer:
5√3
Explanation:
There are two triangles shown in the image.
First one is a 45°-45°-90° right triangle with side lengths represented with a-a-a√2 respectively to the angle measures.
The second triangle is 30°-60°-90° special right triangle with side lengths represented with b-b√3-2b respectively to the angle measures.
In first triangle hypotenuse (the side length represented with a√2) is given as 10√2 so a = 10.
This is also the measure of hypotenuse for the second triangle which is represented with 2b, so b = 5 in this case.
x is the side length that sees angle measure 60° which we said is represented with b√3, we said b = 5 so the value of x = 5√3 the answer is the first option.