7 2 | × | 120 | + | 16 5 | ( | x | − | 120 | ) | = | 7 2 | × | 120 | + | 16 5 | ( | 400 | − | x | − | 120 | ) |
| Left side of the equation = | 420 | + | 16 5 | ( | x | − | 120 | ) |
| 420 | + | 16 5 | ( | x | − | 120 | ) | = | 7 2 | × | 120 | + | 16 5 | ( | 400 | − | x | − | 120 | ) |
| Left side of the equation = | 420 | + | 16 5 | x | − | 16 5 | × | 120 |
| = | 420 | + | 16 5 | x | − | 384 |
| = | 36 | + | 16 5 | x |
| 36 | + | 16 5 | x | = | 7 2 | × | 120 | + | 16 5 | ( | 400 | − | x | − | 120 | ) |
| Right side of the equation = | 420 | + | 16 5 | ( | 400 | − | x | − | 120 | ) |
| 36 | + | 16 5 | x | = | 420 | + | 16 5 | ( | 400 | − | x | − | 120 | ) |
| Right side of the equation = | 420 | + | 16 5 | × | 400 | − | 16 5 | x | − | 16 5 | × | 120 |
| = | 420 | + | 1280 | − | 16 5 | x | − | 384 |
| = | 1316 | − | 16 5 | x |
| 36 | + | 16 5 | x | = | 1316 | − | 16 5 | x |
16 5 | x | + | 16 5 | x | = | 1316 | − | 36 |
32 5 | x | = | 1316 | − | 36 |
32 5 | x | = | 1280 |
| x | = | 1280 | ÷ | 32 5 |
| = | 1280 | × | 5 32 |
| = | 40 | × | 5 |
| x | = | 200 |