Two cars leave Memphis from exactly the same spot at exactly the same time, one traveling north at an average speed of 70 mph and the other traveling south at an average speed of 65 mph. Approximately how long does it take before the cars are 270 miles apart?

2 hours

Explanation:

One car is travelling north and other is travelling south. This means the two cars are travelling in opposite directions. When two objects move in opposite direction their relative speed is the sum of speed of both objects.

So, the relative speed in this case will be = 70 + 65 = 135 mph

In context of this problem we can say that 270 miles distance is to be covered at a speed of 135 mph.

Since,

Distance = Speed x Time

We can write:

270 miles = 135 mph x Time

Time = 2 hours

Thus, we can conclude that the cars will be 270 miles apart in 2 hours