Answer:
x=18
Explanation:
First, using the Pythagorean theorem, you can make the equation 10^2+y^2=26^2. You can solve this to get y=24. Another way to solve for the value of y is to use your Pythagorean triples! (in this case, all the values are double the values of the Pythagorean triple 5, 12, 13).
Next, you can use the Pythagorean theorem again to get the equation 24^2+x^2=30^2. Solving it, you would get x=18.
Hope this helps!