This is the boss. No calculator — the numbers are picked to fit in your head, the way a good exam question always secretly is. One road trip, three legs, and every answer feeds the next: each leg's time, then the total distance, then the trip's honest average. Write each line down as you go — one early slip rides along for the whole trip.

Everything from this chapter is in the car: $t = \dfrac{d}{v}$ three times, an addition or two, and the whole-trip rule from last lesson. 5★ under par here is the chapter crown. Buckle up.