1. **State the problem:** Madelyn rode her motorcycle at 85 kilometers per hour for 4 hours. 2. We want to find the distance she rode while the car was behind her for half of the total time. 3. Calculate half of the total time: $$ \frac{1}{2} \times 4 = 2 \text{ hours} $$ 4. Calculate the distance Madelyn rode during these 2 hours by multiplying speed and time: $$ 85 \text{ km/h} \times 2 \text{ hours} = 170 \text{ kilometers} $$ 5. **Answer:** Madelyn rode 170 kilometers while the car was behind her.