| ( | 5 | − | 1 | ) | × | 70 100 | x | + | ( | 5 | × | 2 5 | − | 1 | ) | × | 30 100 | x | = | 3100 |
| Left side of the equation = | 5 | × | 70 100 | x | − | 1 | × | 70 100 | x | + | ( | 5 | × | 2 5 | − | 1 | ) | × | 30 100 | x |
| = | 7 2 | x | − | 7 10 | x | + | ( | 5 | × | 2 5 | − | 1 | ) | × | 30 100 | x |
| = | 14 5 | x | + | ( | 5 | × | 2 5 | − | 1 | ) | × | 30 100 | x |
| = | 14 5 | x | + | 5 | × | 2 5 | × | 30 100 | x | − | 1 | × | 30 100 | x |
| = | 14 5 | x | + | 3 5 | x | − | 3 10 | x |
| = | 31 10 | x |
31 10 | x | = | 3100 |
| x | = | 3100 | ÷ | 31 10 |
| = | 3100 | × | 10 31 |
| = | 100 | × | 10 |
| x | = | 1000 |