| ( | ( | x | − | 20 | ) | × | 3 4 | − | 15 | ) | ÷ | 140 | = | ( | ( | x | − | 35 | ) | × | 3 4 | − | 15 | ) | ÷ | 80 |
| Left side of the equation = | ( | x | − | 20 | ) | × | 3 4 | × | 1 140 | − | 15 | × | 1 140 |
| = | ( | x | − | 20 | ) | × | 3 560 | − | 3 28 |
| = | x | × | 3 560 | − | 20 | × | 3 560 | − | 3 28 |
| = | x | × | 3 560 | − | 3 28 | − | 3 28 |
| = | 3 560 | x | − | 3 14 |
3 560 | x | − | 3 14 | = | ( | ( | x | − | 35 | ) | × | 3 4 | − | 15 | ) | ÷ | 80 |
| Right side of the equation = | ( | x | − | 35 | ) | × | 3 4 | × | 1 80 | − | 15 | × | 1 80 |
| = | ( | x | − | 35 | ) | × | 3 320 | − | 3 16 |
| = | x | × | 3 320 | − | 35 | × | 3 320 | − | 3 16 |
| = | x | × | 3 320 | − | 21 64 | − | 3 16 |
| = | 3 320 | x | − | 33 64 |
3 560 | x | − | 3 14 | = | 3 320 | x | − | 33 64 |
3 560 | x | − | 3 320 | x | = | - | 33 64 | + | 3 14 |
| - | 9 2240 | x | = | - | 33 64 | + | 3 14 |
| - | 9 2240 | x | = | - | 135 448 |
135 448 | = | 9 2240 | x |
9 2240 | x | = | 135 448 |
| x | = | 135 448 | ÷ | 9 2240 |
| = | 135 448 | × | 2240 9 |
| = | 15 | × | 5 |
| x | = | 75 |