| 4 | 4 | ||
czasu, który upłynął od północy, równa się | czasu, który jeszcze pozostał do | ||
| 9 | 7 |
| 4 | 4 | ||
x= | (12−x) | ||
| 9 | 7 |

| 4 | 4 | ||
t1= | t2 | ||
| 9 | 7 |
| 4t1 | 4t2 | ||
= | |||
| 9 | 7 |
| 36 | ||
t1= | t2 | |
| 28 |
| 7 | ||
t1= | t2 /:t2 | |
| 9 |
| t1 | 7 | ||
= | |||
| t2 | 9 |
| 12 | 3 | |||
t= | = | h | ||
| 16 | 4 |
| 3 | ||
7t=7* | h = 7*45 min = 315 min = 5 h 15 min | |
| 4 |
| 9 | ||
t1= | t2 | |
| 7 |
| t1 | 9 | ||
= | |||
| t2 | 7 |
| 3 | ||
t= | h = 45 min | |
| 4 |