Answer:
let t = no of minutes when they are at the same altitude
:
52200 - 3300t = 2500t
52200 = 3300t + 2500t
52200 = 5800t
t = 52200/5800
t = 9 minutes they will be at the same altitude
:
The altitude:
9*2500 = 22500 ft
:
Check on other train
52200 - 9(3300) =
52200 - 29700 = 22500 ft