| ( | 68 | − | 45 | ) | ÷ | ( | 45 | − | 40 | ) | = | ( | 85 | − | t | ) | ÷ | ( | t | − | 71 | ) |
| Multiply both sides of the equation by: | ( | 45 | − | 40 | ) | , | ( | t | − | 71 | ) |
| ( | 68 | − | 45 | ) | ( | t | − | 71 | ) | = | ( | 85 | − | t | ) | ( | 45 | − | 40 | ) |
| 68 | ( | t | − | 71 | ) | − | 45 | ( | t | − | 71 | ) | = | ( | 85 | − | t | ) | ( | 45 | − | 40 | ) |
| 68 | ( | t | − | 71 | ) | − | 45 | ( | t | − | 71 | ) | = | 85 | ( | 45 | − | 40 | ) | − | t | ( | 45 | − | 40 | ) |
| 68 | t | − | 68 | × | 71 | − | 45 | ( | t | − | 71 | ) | = | 85 | ( | 45 | − | 40 | ) | − | t | ( | 45 | − | 40 | ) |
| 68 | t | − | 68 | × | 71 | − | 45 | ( | t | − | 71 | ) | = | 85 | × | 45 | − | 85 | × | 40 | − | t | ( | 45 | − | 40 | ) |
| 68 | t | − | 4828 | − | 45 | ( | t | − | 71 | ) | = | 3825 | − | 3400 | − | t | ( | 45 | − | 40 | ) |
| 68 | t | − | 4828 | − | 45 | ( | t | − | 71 | ) | = | 425 | − | t | ( | 45 | − | 40 | ) |
| 68 | t | − | 4828 | − | 45 | t | + | 45 | × | 71 | = | 425 | − | t | ( | 45 | − | 40 | ) |
| 68 | t | − | 4828 | − | 45 | t | + | 45 | × | 71 | = | 425 | − | t | × | 45 | + | t | × | 40 |
| 68 | t | − | 4828 | − | 45 | t | + | 3195 | = | 425 | − | t | × | 45 | + | t | × | 40 |
| 23 | t | − | 1633 | = | 425 | − | 5 | t |
| 23 | t | + | 5 | t | = | 425 | + | 1633 |
| 28 | t | = | 425 | + | 1633 |
| 28 | t | = | 2058 |
| t | = | 2058 | ÷ | 28 |
| = | 2058 | × | 1 28 |
| = | 147 | × | 1 2 |
| t | = | 147 2 |
| t | = | 73.5 |