Answer:
The distance between the two cities is 720 miles
Step-by-step explanation:
Here, we want to calculate the distance between the two cities
Since the speed on both legs of the journey is not the same, it means she will take less time traveling the same distance at a higher speed
Mathematically, distance = speed * time
Let the time spent going be x hours
The time spent coming will be (30-x) hours since 30 is the total
The distance of going will be;
40 * x = 40x
The distance of coming will be;
60(30-x)
Since these distances are equal, we equate both;
40x = 60(30-x)
40x = 1800 - 60x
60x + 40x = 1800
100x = 1800
x = 1800/100
x = 18 hours
The distance = 40 mph * 18 h = 720 miles
