The plane traveling 200 mph, started 4 hours earlier.
As at when they meet, let the 550 mph, have traveled for x hours.
The 200 mph would have traveled (x + 4) hours, since it started 4 hours earlier.
As at when they met, the distance covered is the same:
Distance = Speed * hour
550x = 200(x + 4)
550x = 200x + 200*4
550x = 200x + 800
550x - 200x = 800
350x = 800
x = 800/350
x = 16/7 hours.
The distance travelled = 550x = 550 * 16/7 = 8800/7 miles
The distance = 8800 / 7 miles or ≈ 1257.14 miles
Hope this explains it.
