| 19 | ( | t | − | 56 | ) | = | 9 | ( | 80 | − | t | ) |
| 方程左边 = | 19 | t | − | 19 | × | 56 |
| = | 19 | t | − | 1064 |
| 19 | t | − | 1064 | = | 9 | ( | 80 | − | t | ) |
| 方程右边 = | 9 | × | 80 | − | 9 | t |
| = | 720 | − | 9 | t |
| 19 | t | − | 1064 | = | 720 | − | 9 | t |
| 19 | t | + | 9 | t | = | 720 | + | 1064 |
| 28 | t | = | 720 | + | 1064 |
| 28 | t | = | 1784 |
| t | = | 1784 | ÷ | 28 |
| = | 1784 | × | 1 28 |
| = | 446 | × | 1 7 |
| t | = | 446 7 |
| t | = | 63.714286 |