A suspect in a high speed chase enters I-8 Eastbound at 70 miles per hour. 21 minutes later a highway patrolman enters I-8 Eastbound at the same location at 77 miles per hour. How long until the officer catches up to the suspect?

The model is $LaTeX: \displaystyle d=rt$ . The suspect has a 21 minute head start. The equation for the distance traveled by the suspect is $LaTeX: \displaystyle d=70(t + 21)$ . The highway patrolman has traveled $LaTeX: \displaystyle d=77 t$ . To catch the suspect the distances traveled must be equal. This gives the equation is $LaTeX: \displaystyle 70 t + 1470=77 t$ . Solving gives that it will take $LaTeX: \displaystyle 210$ minutes to catch the suspect.