1. **Stating the problem:** John drives 200 km at steady speeds of 60 km/h and 100 km/h. The graph shows fuel consumption for these speeds: segment l1 ends at (25 km, 275 litres) for 60 km/h, and segment l2 ends at (40 km, 340 litres) for 100 km/h. 2. **Formula and rules:** Fuel consumption rate (litres per km) = \frac{Fuel}{Distance}. Total fuel used for 200 km = Fuel consumption rate \times 200. Cost = Fuel used \times 1.45. 3. **Calculate fuel consumption rates:** For 60 km/h: $$\text{Rate}_{60} = \frac{275}{25} = 11 \text{ litres/km}$$ For 100 km/h: $$\text{Rate}_{100} = \frac{340}{40} = 8.5 \text{ litres/km}$$ 4. **Calculate total fuel used for 200 km:** For 60 km/h: $$\text{Fuel}_{60} = 11 \times 200 = 2200 \text{ litres}$$ For 100 km/h: $$\text{Fuel}_{100} = 8.5 \times 200 = 1700 \text{ litres}$$ 5. **Calculate total cost for each speed:** For 60 km/h: $$\text{Cost}_{60} = 2200 \times 1.45 = 3190$$ For 100 km/h: $$\text{Cost}_{100} = 1700 \times 1.45 = 2465$$ 6. **Calculate how much cheaper the journey is at 60 km/h than at 100 km/h:** $$\text{Difference} = 3190 - 2465 = 725$$ **Answer:** The journey at 100 km/h is 725 cheaper than at 60 km/h. (Note: Since the question asks how much cheaper the journey at 60 km/h is than at 100 km/h, and the cost at 60 km/h is higher, the journey at 60 km/h is actually more expensive by 725.)