| 13 | ( | t | − | 56 | ) | = | 15 | ( | 80 | − | t | ) |
| Left side of the equation = | 13 | t | − | 13 | × | 56 |
| = | 13 | t | − | 728 |
| 13 | t | − | 728 | = | 15 | ( | 80 | − | t | ) |
| Right side of the equation = | 15 | × | 80 | − | 15 | t |
| = | 1200 | − | 15 | t |
| 13 | t | − | 728 | = | 1200 | − | 15 | t |
| 13 | t | + | 15 | t | = | 1200 | + | 728 |
| 28 | t | = | 1200 | + | 728 |
| 28 | t | = | 1928 |
| t | = | 1928 | ÷ | 28 |
| = | 1928 | × | 1 28 |
| = | 482 | × | 1 7 |
| t | = | 482 7 |
| t | = | 68.857143 |