Question 5764
When one car is slower than another car in this kind of problem, it's always a good idea to give the slower one the variable.



S = Speed of the slower car.
2S = Speed of the faster car (because it's twice as fast as the slower car).
T = 3 hours.


Distance of the slower car in 3 hours = 3S
Distance of the faster car in 3 hours = 3(2S) = 6S


In this case, the faster car is ahead and the slower car is behind. In order for the slower car's distance to match up with the car ahead of him, we need to add the 96 miles to the slower car's distance. The equation would be:


{{{ 3S + 96 = 6S }}}


CAUTION!!! It's common to subtract the 96 miles from the slower car. But it's already behind. You don't need to subtract 96 miles from its current distance. You actually have to ADD it to equal the distance traveled by the faster car.


Once solved, the slower car's speed is 32 miles per hour. If the faster car's speed is double the slower car's speed, then the faster car's speed is 64 miles per hour.