| 12000 | ÷ | ( | 80 | − | 20 | x | ) | + | 13200 | ÷ | ( | 80 | + | 15 | x | ) | = | 160 |
| Multiply both sides of the equation by: | ( | 80 | − | 20 | x | ) |
| 12000 | + | 13200 | ÷ | ( | 80 | + | 15 | x | ) | × | ( | 80 | − | 20 | x | ) | = | 160 | ( | 80 | − | 20 | x | ) |
| 12000 | + | 13200 | ÷ | ( | 80 | + | 15 | x | ) | × | 80 | − | 13200 | ÷ | ( | 80 | + | 15 | x | ) | × | 20 | x | = | 160 | ( | 80 | − | 20 | x | ) |
| 12000 | + | 13200 | ÷ | ( | 80 | + | 15 | x | ) | × | 80 | − | 13200 | ÷ | ( | 80 | + | 15 | x | ) | × | 20 | x | = | 160 | × | 80 | − | 160 | × | 20 | x |
| 12000 | + | 1056000 | ÷ | ( | 80 | + | 15 | x | ) | − | 264000 | ÷ | ( | 80 | + | 15 | x | ) | × | x | = | 12800 | − | 3200 | x |
| Multiply both sides of the equation by: | ( | 80 | + | 15 | x | ) |
| 12000 | ( | 80 | + | 15 | x | ) | + | 1056000 | − | 264000 | x | = | 12800 | ( | 80 | + | 15 | x | ) | − | 3200 | x | ( | 80 | + | 15 | x | ) |
| 12000 | × | 80 | + | 12000 | × | 15 | x | + | 1056000 | − | 264000 | x | = | 12800 | ( | 80 | + | 15 | x | ) | − | 3200 | x | ( | 80 | + | 15 | x | ) |
| 12000 | × | 80 | + | 12000 | × | 15 | x | + | 1056000 | − | 264000 | x | = | 12800 | × | 80 | + | 12800 | × | 15 | x | − | 3200 | x | ( | 80 | + | 15 | x | ) |
| 960000 | + | 180000 | x | + | 1056000 | − | 264000 | x | = | 1024000 | + | 192000 | x | − | 3200 | x | ( | 80 | + | 15 | x | ) |
| 2016000 | − | 84000 | x | = | 1024000 | + | 192000 | x | − | 3200 | x | ( | 80 | + | 15 | x | ) |
| 2016000 | − | 84000 | x | = | 1024000 | + | 192000 | x | − | 3200 | x | × | 80 | − | 3200 | x | × | 15 | x |
| 2016000 | − | 84000 | x | = | 1024000 | + | 192000 | x | − | 256000 | x | − | 48000 | x | x |
| 2016000 | − | 84000 | x | = | 1024000 | − | 64000 | x | − | 48000 | x | x |