Answer:
600 ft
Explanation:
Alice's Average Speed=280 ft/min
Dave's Average Speed=320 ft/min.
Distance = Average Speed X Time
In 1 minute, their distances from their starting point is determined below.
Alice's Distance=280 X 1=280ft
Dave's Distance= 320 X 1=320ft
Since they walk in opposite direction, their distance from each other will be the sum of their distances from the starting point.
Distance of Alice from Dave=280+320=600 ft
In 1 minute, they were 600 ft apart.