Solve this for the brainlist

Answer:
22.4
Step-by-step explanation:
using altitude theorem, the height of the triangle is 20
let y = height
10/y = y/40
y² = 400
y = [tex]\sqrt{400}[/tex] or 20
Now we can us the Pythagorean Theorem to find 'x':
10² + 20² = x²
100 + 400 = x²
x=[tex]\sqrt{500}[/tex] ≈ 22.4