Explanation:

Let height be h and first point distance is x

Second point distance is x+500  m

 tan 30 ° =1/√3,tan60 °=√3

1/√3 =h/x,  √3=h/x+500

x=√3 h …..  equation 1

√3x+500 √3 =h   ….equation2

Solving equation 1 and 2

√3  × √3h+500√3=h

3h+500 √3=h

2h=-500 √3

h=250 √3  (taking magnitude)