Answer:
280t + 320t = 1,000
Explanation:
At 10:00 a.m. two planes leave an airport. If the northbound plane flies at 280 mph and the southbound at 320 mph
Let 't' be the time taken when they are 1000 miles apart
the northbound plane flies at 280 mph
Distance = speed * time
distance covered by northbound plane D1= 280 * t= 280t
the southbound at 320 mph
distance covered by southbound plane D2=320 t
Distance is 1000 miles apart
D1 + D2= 1000
280t + 320t = 1,000