This is a Kaplan800
question. Additive rates
OA is B
Right. Whenever you've got two bodies moving in the opposite direction, you can add their rates (you subtract when they're going in the same direction).
So these two planes need to cover 300 miles to meet, at a combined rate of 360 mph.
Then you can use whatever method you want. I think it's safest to use d = rt:
300 = 360t
300/360 = t
5/6 hours =