Since we know that LCM of both 625&575 is 14375, we must find the hours it took for both planes to arrive at this same destination.
Plane 1(625): Took 23 hours to arrive.
Plane 2(575): Took 25 hours to arrive.
Therefore, the answer should be from 23-25 hours to arrive or if looking for middle number, 24 hours exactly.
Hope this helps.