Answer:
Time taken them to meet = 1.429 hours.
Explanation:
Speed of first plane = 40 mph
Speed of second plane = 100 mph
Distance between planes = 200 miles
If two objects with speed v and u are flying towards each other, their relative speed = v + u
So here relative speed = 40 + 100 = 140 mph
Time taken to meet = Distance/Speed = 200/140 = 1.429 hours.
Time taken them to meet = 1.429 hours.