Solve $d=300\text{ mi},v_1=60\text{ mph},v_2=40\text{ mph}$

Step-by-step solution

1. Step 1 · Relative speed
   $$v_{\text{closing}}=60+40=100\text{ mph}$$

   Assume both start at the same time, drive toward each other on the same road at constant speeds, and do not stop.

2. Step 2 · Time = distance / speed
   $$t=\frac{300}{100}=3\text{ hours}$$

   Miles divided by miles per hour gives hours.

3. Step 3 · Distance check
   $$60(3)+40(3)=180+120=300$$

   Together the cars cover the full initial separation.