| 80 | × | 180 | = | ( | 80 | + | 70 | ) | × | 8 | t |
| Left side of the equation = | 14400 |
| 14400 | = | ( | 80 | + | 70 | ) | × | 8 | t |
| Right side of the equation = | 80 | × | 8 | t | + | 70 | × | 8 | t |
| = | 640 | t | + | 560 | t |
| = | 1200 | t |
| 14400 | = | 1200 | t |
| - | 1200 | t | = | - | 14400 |
| 14400 | = | 1200 | t |
| 1200 | t | = | 14400 |
| t | = | 14400 | ÷ | 1200 |
| = | 14400 | × | 1 1200 |
| = | 12 | × | 1 |
| t | = | 12 |