| ( | 10 | + | 15 | x | ÷ | x | + | 15 | ) | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | = | 12 |
| 10 | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | + | 15 | x | ÷ | x | × | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | + | 15 | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | = | 12 |
| 10 | × | 12 | x | + | 10 | × | 210 | ÷ | 25 | × | x | + | 10 | × | 150 | + | 15 | × | 1 | ÷ | 1 | = | 12 |
| 120 | x | + | 84 | x | + | 1500 | + | 15 | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | + | 15 | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | = | 12 |
| 204 | x | + | 1500 | + | 15 | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | + | 15 | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | = | 12 |
| 204 | x | + | 1500 | + | 15 | × | 12 | x | + | 15 | × | 210 | ÷ | 25 | × | x | + | 15 | × | 150 | = | 12 |
| 204 | x | + | 1500 | + | 180 | x | + | 126 | x | + | 2250 | + | 15 | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | = | 12 |
| 510 | x | + | 3750 | + | 15 | ( | 12 | x | + | 210 | ÷ | 25 | × | x | + | 150 | ) | = | 12 |
| 510 | x | + | 3750 | + | 15 | × | 12 | x | + | 15 | × | 210 | ÷ | 25 | × | x | + | 15 | × | 150 | = | 12 |
| 510 | x | + | 3750 | + | 180 | x | + | 126 | x | + | 2250 | = | 12 |
| 816 | x | + | 6000 | = | 12 |
| 816 | x | = | 12 | − | 6000 |
| 816 | x | = | - | 5988 |
| x | = | - | 5988 | ÷ | 816 |
| = | - | 5988 | × | 1 816 |
| = | - | 499 | × | 1 68 |
| x | = | - | 499 68 |
| x | = | - 7.338235 |