Two cars leave a gas station at the same time, one traveling north and the other south. the northbound car travels at 50 mph. after 3 hours the cars are 345 miles apart. how fast is the southbound car traveling? a. 60 mph b. 65 mph c. 70 mph d. 75 mph

For this case we have:

We define the following variable

x : Speed of the car in South direction

By definition, we know that:

For the car in north direction:

For the car in south direction:

The distance between both cars, after 3 hours, is:

So, we have:

Clearing x;

Thus, the speed of the car in the south direction is

Option B