| ( | 27 | − | 27 | ) | ÷ | ( | 27 | − | 18 | ) | = | ( | 40 | − | t | ) | ÷ | ( | t | − | 30 | ) |
| Multiply both sides of the equation by: | ( | 27 | − | 18 | ) | , | ( | t | − | 30 | ) |
| ( | 27 | − | 27 | ) | ( | t | − | 30 | ) | = | ( | 40 | − | t | ) | ( | 27 | − | 18 | ) |
| 27 | ( | t | − | 30 | ) | − | 27 | ( | t | − | 30 | ) | = | ( | 40 | − | t | ) | ( | 27 | − | 18 | ) |
| 27 | ( | t | − | 30 | ) | − | 27 | ( | t | − | 30 | ) | = | 40 | ( | 27 | − | 18 | ) | − | t | ( | 27 | − | 18 | ) |
| 27 | t | − | 27 | × | 30 | − | 27 | ( | t | − | 30 | ) | = | 40 | ( | 27 | − | 18 | ) | − | t | ( | 27 | − | 18 | ) |
| 27 | t | − | 27 | × | 30 | − | 27 | ( | t | − | 30 | ) | = | 40 | × | 27 | − | 40 | × | 18 | − | t | ( | 27 | − | 18 | ) |
| 27 | t | − | 810 | − | 27 | ( | t | − | 30 | ) | = | 1080 | − | 720 | − | t | ( | 27 | − | 18 | ) |
| 27 | t | − | 810 | − | 27 | ( | t | − | 30 | ) | = | 360 | − | t | ( | 27 | − | 18 | ) |
| 27 | t | − | 810 | − | 27 | t | + | 27 | × | 30 | = | 360 | − | t | ( | 27 | − | 18 | ) |
| 27 | t | − | 810 | − | 27 | t | + | 27 | × | 30 | = | 360 | − | t | × | 27 | + | t | × | 18 |
| 27 | t | − | 810 | − | 27 | t | + | 810 | = | 360 | − | t | × | 27 | + | t | × | 18 |
| 0 | t | − | 0 | = | 360 | − | 9 | t |
| 9 | t | = | 360 | + | 0 |
| 9 | t | = | 360 |
| t | = | 360 | ÷ | 9 |
| = | 360 | × | 1 9 |
| = | 40 | × | 1 |
| t | = | 40 |