Two cars leave the same point travelling in opposite directions at 50 and 70 mph. How long until they are 360 miles apart?

Problem: Two cars leave the same point traveling in opposite directions at $50\text{ mph}$ and $70\text{ mph}$. How long until they are $360\text{ miles}$ apart?

Steps

1. Calculate the combined rate of separation
   $$50 + 70 = 120$$
2. Set up the distance equation using $d = rt$
   $$120t = 360$$
3. Divide both sides by 120
   $$t = \frac{360}{120}$$
4. Simplify the fraction
   $$t = 3$$