| 276 | ÷ | 50 | + | a | = | 324 | ÷ | 50 | − | a |
| Left side of the equation = | 138 25 | + | a |
138 25 | + | a | = | 324 | ÷ | 50 | − | a |
| Right side of the equation = | 162 25 | − | a |
138 25 | + | a | = | 162 25 | − | a |
| a | + | a | = | 162 25 | − | 138 25 |
| 2 | a | = | 162 25 | − | 138 25 |
| 2 | a | = | 24 25 |
| a | = | 24 25 | ÷ | 2 |
| = | 24 25 | × | 1 2 |
| = | 12 25 | × | 1 |
| a | = | 12 25 |
| a | = | 0.48 |