| 1000 | m | × | 20 | + | 1000 | m | ( | 500 | − | m | ) | × | 80 | − | 3000000 | = | 1000 | × | 500 | × | 70 |
| Left side of the equation = | 20000 | m | + | 80000 | m | ( | 500 | − | m | ) | − | 3000000 |
| 20000 | m | + | 80000 | m | ( | 500 | − | m | ) | − | 3000000 | = | 1000 | × | 500 | × | 70 |
| Left side of the equation = | 20000 | m | + | 80000 | m | × | 500 | − | 80000 | m | m | − | 3000000 |
| = | 20000 | m | + | 40000000 | m | − | 80000 | m | m | − | 3000000 |
| = | 40020000 | m | − | 80000 | m | m | − | 3000000 |
| 40020000 | m | − | 80000 | m | m | − | 3000000 | = | 1000 | × | 500 | × | 70 |
| Right side of the equation = | 35000000 |
| 40020000 | m | − | 80000 | m | m | − | 3000000 | = | 35000000 |