| 15 | + | ( | x | × | 21 20 | + | 5 | ) | + | 0 | + | ( | 15 | × | 21 125 | ) | = | 1167 50 |
| 方程左边 = | 15 | + | ( | x | × | 21 20 | + | 5 | ) | + | ( | 15 | × | 21 125 | ) |
| 15 | + | ( | x | × | 21 20 | + | 5 | ) | + | ( | 15 | × | 21 125 | ) | = | 1167 50 |
| 方程左边 = | 15 | + | x | × | 21 20 | + | 5 | + | ( | 15 | × | 21 125 | ) |
| = | 20 | + | 21 20 | x | + | ( | 15 | × | 21 125 | ) |
| = | 20 | + | 21 20 | x | + | 15 | × | 21 125 |
| = | 20 | + | 21 20 | x | + | 63 25 |
| = | 563 25 | + | 21 20 | x |
563 25 | + | 21 20 | x | = | 1167 50 |
21 20 | x | = | 1167 50 | − | 563 25 |
21 20 | x | = | 41 50 |
| x | = | 41 50 | ÷ | 21 20 |
| = | 41 50 | × | 20 21 |
| = | 41 5 | × | 2 21 |
| x | = | 82 105 |
| x | = | 0.780952 |