| ( | 200 | + | 4 | a | ) | × | 30 | a | = | ( | 30 | + | a | ) | × | 50 | a |
| Left side of the equation = | 200 | × | 30 | a | + | 4 | a | × | 30 | a |
| = | 6000 | a | + | 120 | a | a |
| 6000 | a | + | 120 | a | a | = | ( | 30 | + | a | ) | × | 50 | a |
| Right side of the equation = | 30 | × | 50 | a | + | a | × | 50 | a |
| = | 1500 | a | + | a | × | 50 | a |
| 6000 | a | + | 120 | a | a | = | 1500 | a | + | a | × | 50 | a |
| a1=0 |