It is apparent that fox travelled 16 m which is same as distance travelled by eagle. Now the eagle ascends to a height x m and reaches A. Distance travelled by eagle is √(10²+(6+x)²) + x.
This is equal to 16 m. Then 100 + 36 + 12x + x² = 256 + x² - 32x⇒ = 0. Then x=120/44 = 30/11m.