A flag staff 5m high stands on a building 25m high. To an observer at a height of 30m, the flag staff and the building subtend equal angles. The distance of the observer from the top of the flag staff is:
1
\( 5\sqrt{\frac{3}{2}} \)
2
\( \sqrt{\frac{3}{2}}\)
3
\(\frac{2}{3}\)
4
\( \sqrt{\frac{2}{3}}\)