| ( | 191 | + | 323 | ) | ÷ | 31 | × | x | + | 217 | ÷ | 31 | × | ( | x | + | 15 | ) | + | 124 | ÷ | 31 | × | ( | x | + | 30 | ) | = | 1980 |
| 方程左边 = | ( | 191 | + | 323 | ) | × | 1 31 | x | + | 7 | ( | x | + | 15 | ) | + | 4 | ( | x | + | 30 | ) |
| ( | 191 | + | 323 | ) | × | 1 31 | x | + | 7 | ( | x | + | 15 | ) | + | 4 | ( | x | + | 30 | ) | = | 1980 |
| 方程左边 = | 191 | × | 1 31 | x | + | 323 | × | 1 31 | x | + | 7 | ( | x | + | 15 | ) | + | 4 | ( | x | + | 30 | ) |
| = | 191 31 | x | + | 323 31 | x | + | 7 | ( | x | + | 15 | ) | + | 4 | ( | x | + | 30 | ) |
| = | 514 31 | x | + | 7 | ( | x | + | 15 | ) | + | 4 | ( | x | + | 30 | ) |
| = | 514 31 | x | + | 7 | x | + | 7 | × | 15 | + | 4 | ( | x | + | 30 | ) |
| = | 514 31 | x | + | 7 | x | + | 105 | + | 4 | ( | x | + | 30 | ) |
| = | 731 31 | x | + | 105 | + | 4 | ( | x | + | 30 | ) |
| = | 731 31 | x | + | 105 | + | 4 | x | + | 4 | × | 30 |
| = | 731 31 | x | + | 105 | + | 4 | x | + | 120 |
| = | 855 31 | x | + | 225 |
855 31 | x | + | 225 | = | 1980 |
855 31 | x | = | 1980 | − | 225 |
855 31 | x | = | 1755 |
| x | = | 1755 | ÷ | 855 31 |
| = | 1755 | × | 31 855 |
| = | 39 | × | 31 19 |
| x | = | 1209 19 |
| x | = | 63.631579 |