720 km
| Hour | 120kmh Motorcycle | 90 kmh motorcycle |
| 0 | 0 | 0 |
| 1 | 120 | 90 |
| 2 | 240 | 180 |
| 3 | 360 | 270 |
| 4 | 480 | 360 |
| 5 | 600 | 450 |
| 6 | 720 | 540 |
| 7 | 840 | 630 |
| 8 | 960 | 720 |
| 9 | 1080 | 810 |
| 10 | 1200 | 900 |
| 11 | 1320 | 990 |
| 12 | 1440 | 1080 |
Look at the graph. Look at hour 12. The faster motorcycle traveled twice as far the slower motorcycle had 4 hours ago.
Look at how far the slower motorcycle went at hour 8. 720 km
I hope this was useful :)